diff --git a/feca_mailshots_plugin/feca_mailshots_plugin.php b/feca_mailshots_plugin/feca_mailshots_plugin.php
index 264f7ac..c4c123c 100644
--- a/feca_mailshots_plugin/feca_mailshots_plugin.php
+++ b/feca_mailshots_plugin/feca_mailshots_plugin.php
@@ -3,7 +3,7 @@
  * Plugin Name: FECA Mailshots
  * Plugin URI: https://fenedge.co.uk/
  * Description: FECA mailshots plugin.
- * Version: 1.0.33
+ * Version: 1.1.0
  * Requires at least: 6.0
  * Requires PHP: 7.4
  * Author: FECA
diff --git a/feca_mailshots_plugin/readme.txt b/feca_mailshots_plugin/readme.txt
index ff16e49..ba8001a 100644
--- a/feca_mailshots_plugin/readme.txt
+++ b/feca_mailshots_plugin/readme.txt
@@ -3,7 +3,7 @@ Contributors: feca
 Requires at least: 6.0
 Tested up to: 6.5
 Requires PHP: 7.4
-Stable tag: 1.0.0
+Stable tag: 1.1.0
 License: GPLv2 or later
 License URI: https://www.gnu.org/licenses/gpl-2.0.html
 
diff --git a/feca_mailshots_plugin/src/Admin/AdminRequestHelpers.php b/feca_mailshots_plugin/src/Admin/AdminRequestHelpers.php
index db3bb59..c04fa91 100644
--- a/feca_mailshots_plugin/src/Admin/AdminRequestHelpers.php
+++ b/feca_mailshots_plugin/src/Admin/AdminRequestHelpers.php
@@ -35,6 +35,8 @@ trait AdminRequestHelpers
             . '.feca-mailshots-admin .feca-minw-240{min-width:240px;}'
             . '.feca-mailshots-admin .feca-control input,.feca-mailshots-admin .feca-control select,.feca-mailshots-admin .feca-control textarea{margin:0;}'
             . '.feca-mailshots-admin .feca-control label{white-space:nowrap;padding-left:var(--feca-space-1);font-weight:600;}'
+            . '.feca-mailshots-admin .feca-inline-control-group{display:flex;align-items:flex-end;gap:var(--feca-space-2);flex-wrap:wrap;padding:8px 10px;border:1px solid #dcdcde;background:#f6f7f7;border-radius:var(--feca-radius);}'
+            . '.feca-mailshots-admin .feca-inline-control-group .feca-control{padding:0;}'
             . '.feca-mailshots-admin .feca-button-row{display:flex;gap:var(--feca-space-2);align-items:center;flex-wrap:wrap;margin-top:var(--feca-space-3);margin-bottom:0;padding:0;}'
             . '.feca-mailshots-admin .feca-button-row .button{margin:0 !important;}'
             . '.feca-mailshots-admin .feca-button-danger{color:#b32d2e;border-color:#d63638;}'
@@ -105,6 +107,7 @@ trait AdminRequestHelpers
             . '@media (max-width: 782px){'
             . '.feca-mailshots-admin .feca-control-row{display:block;}'
             . '.feca-mailshots-admin .feca-control{min-width:0;width:100%;}'
+            . '.feca-mailshots-admin .feca-inline-control-group{display:block;}'
             . '}'
             . '</style>';
     }
diff --git a/feca_mailshots_plugin/src/Admin/MailshotTestAdminPage.php b/feca_mailshots_plugin/src/Admin/MailshotTestAdminPage.php
index bcca5a6..d415051 100644
--- a/feca_mailshots_plugin/src/Admin/MailshotTestAdminPage.php
+++ b/feca_mailshots_plugin/src/Admin/MailshotTestAdminPage.php
@@ -17,6 +17,7 @@ final class MailshotTestAdminPage
     private const NONCE_ACTION = 'feca_mailshots_test';
     private const DOWNLOAD_MEMORY_LIMIT_ENV = 'FECA_MAILSHOTS_DOWNLOAD_MEMORY_LIMIT';
     private const DOWNLOAD_MEMORY_LIMIT_OPTION = 'feca_mailshots_download_memory_limit';
+    private const DEFAULT_DOWNLOAD_MEMORY_LIMIT = '512M';
 
     /** @var callable(): MailshotRunService */
     private $runServiceFactory;
@@ -54,7 +55,17 @@ final class MailshotTestAdminPage
             return;
         }
 
-        $mailshots = $this->mailshotService()->list();
+        $pageErrors = [];
+        $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+        if ($memoryError !== null) {
+            $pageErrors[] = $memoryError;
+        }
+        try {
+            $mailshots = $this->mailshotService()->list();
+        } catch (\Throwable $e) {
+            $mailshots = [];
+            $pageErrors[] = $this->diagnosticError('Unable to load mailshots', 'loading test page', $e);
+        }
         $selectedMailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
         if ($selectedMailshotId <= 0 && $mailshots !== []) {
             $selectedMailshotId = (int) ($mailshots[0]['id'] ?? 0);
@@ -62,7 +73,15 @@ final class MailshotTestAdminPage
 
         $preview = ['ok' => false, 'rows' => [], 'errors' => ['Create a mailshot before loading recipients.']];
         if ($selectedMailshotId > 0) {
-            $preview = $this->runService()->previewRecipients($selectedMailshotId, 100);
+            try {
+                $preview = $this->runService()->previewRecipients($selectedMailshotId, 100);
+            } catch (\Throwable $e) {
+                $preview = [
+                    'ok' => false,
+                    'rows' => [],
+                    'errors' => [$this->diagnosticError('Recipient preview failed', 'loading recipient sample', $e)],
+                ];
+            }
         }
         $rows = is_array($preview['rows'] ?? null) ? $preview['rows'] : [];
 
@@ -70,7 +89,12 @@ final class MailshotTestAdminPage
         if ($selectedRecipientIndex < -1) {
             $selectedRecipientIndex = 0;
         }
-        $defaultEmail = $this->runService()->defaultTestEmail()['default_test_email'] ?? '';
+        try {
+            $defaultEmail = $this->runService()->defaultTestEmail()['default_test_email'] ?? '';
+        } catch (\Throwable $e) {
+            $defaultEmail = '';
+            $pageErrors[] = $this->diagnosticError('Unable to load default test email', 'loading test page', $e);
+        }
         $testEmail = (string) ($this->wp->requestParam('test_email', (string) $defaultEmail) ?? $defaultEmail);
         $result = $this->result();
         if ((string) ($this->wp->requestParam('render_test', '0') ?? '0') === '1') {
@@ -78,8 +102,12 @@ final class MailshotTestAdminPage
                 $result = ['ok' => false, 'errors' => ['Choose a specific recipient row for Render Test.']];
             } else {
                 try {
-                    $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
-                    $result = $this->runService()->renderTest($selectedMailshotId, $selectedRecipientIndex);
+                    $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+                    if ($memoryError !== null) {
+                        $result = ['ok' => false, 'errors' => [$memoryError]];
+                    } else {
+                        $result = $this->runService()->renderTest($selectedMailshotId, $selectedRecipientIndex);
+                    }
                 } catch (\Throwable $e) {
                     $result = ['ok' => false, 'errors' => ['Render test failed: ' . $e->getMessage()]];
                 }
@@ -93,6 +121,14 @@ final class MailshotTestAdminPage
         echo $this->renderAdminUiStyles();
         echo '<p>Render with a selected recipient context, then optionally send one test email.</p>';
 
+        if ($pageErrors !== []) {
+            echo '<div class="feca-banner feca-banner-error"><strong>Test page diagnostics</strong>';
+            foreach ($pageErrors as $pageError) {
+                echo '<p class="feca-banner-note">' . htmlspecialchars($pageError, ENT_QUOTES) . '</p>';
+            }
+            echo '</div>';
+        }
+
         if ($result !== null) {
             $ok = !empty($result['ok']);
             $bannerClass = $ok ? 'feca-banner-success' : 'feca-banner-error';
@@ -167,13 +203,15 @@ final class MailshotTestAdminPage
             echo '<option value="' . $idx . '"' . $sel . '>' . htmlspecialchars($text) . '</option>';
         }
         echo '</select></div>';
+        echo '<div class="feca-inline-control-group">';
         echo '<div class="feca-control feca-control-min-420">';
         echo '<label for="mst_test_email"><strong>Test email address</strong></label>';
         echo '<input id="mst_test_email" class="regular-text" type="email" name="test_email" value="' . htmlspecialchars($testEmail, ENT_QUOTES) . '">';
         echo '</div>';
-        echo '<div class="feca-control"><label>&nbsp;</label><button class="button" type="submit" name="action" value="feca_mailshots_test_render_ui">Render Test (No Send)</button></div>';
         echo '<div class="feca-control"><label>&nbsp;</label><button class="button button-primary" type="submit" name="action" value="feca_mailshots_test_send_ui" id="mst-send-test-button" onclick="return window.fecaConfirmTestSend ? window.fecaConfirmTestSend() : confirm(\'Send one test email to the entered address?\');">Send Test Email</button></div>';
         echo '</div>';
+        echo '<div class="feca-control"><label>&nbsp;</label><button class="button" type="submit" name="action" value="feca_mailshots_test_render_ui">Render Test (No Send)</button></div>';
+        echo '</div>';
         echo '</form>';
         echo '<script>(function(){';
         echo 'var apiUrl=' . json_encode($this->wp->adminUrl('admin-post.php?action=feca_mailshots_test_api&op=send_test'), JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) . ';';
@@ -181,7 +219,7 @@ final class MailshotTestAdminPage
         echo 'var inlineResult=document.getElementById("mst-inline-result");';
         echo 'var sendButton=document.getElementById("mst-send-test-button");';
         echo 'function showResult(ok,title,lines){if(!inlineResult){return;}var wrap=document.createElement("div");wrap.className="feca-banner "+(ok?"feca-banner-success":"feca-banner-error");var strong=document.createElement("strong");strong.textContent=title;wrap.appendChild(strong);(lines||[]).forEach(function(line){var p=document.createElement("p");p.className="feca-banner-note";p.textContent=String(line||"");wrap.appendChild(p);});inlineResult.innerHTML="";inlineResult.appendChild(wrap);wrap.scrollIntoView({block:"nearest"});}';
-        echo 'if(form){form.addEventListener("submit",function(ev){var submitter=ev.submitter;if(!submitter||String(submitter.value||"")!=="feca_mailshots_test_send_ui"){return;}ev.preventDefault();var payload=new URLSearchParams(new FormData(form));payload.delete("action");if(sendButton){sendButton.disabled=true;}showResult(true,"Sending test email...",["Rendering PDF attachment and sending message."]);fetch(apiUrl,{method:"POST",credentials:"same-origin",headers:{"Content-Type":"application/x-www-form-urlencoded; charset=UTF-8"},body:payload.toString()}).then(function(response){return response.text().then(function(text){var data=null;try{data=JSON.parse(text);}catch(e){return {ok:false,errors:["Send test failed: server returned HTTP "+response.status+" instead of JSON. Check the WordPress/PHP error log for the underlying fatal error."]};}if(!response.ok&&data&&data.ok!==false){data.ok=false;}return data;});}).then(function(data){if(data&&data.ok){var lines=[];if(data.sent_to){lines.push("Sent to: "+data.sent_to);}if(data.sent_at){lines.push("Sent at: "+data.sent_at);}if(data.warnings&&data.warnings.length){lines=lines.concat(data.warnings.map(function(w){return "Warning: "+w;}));}showResult(true,"Test action succeeded.",lines.length?lines:["Sent."]);return;}var errors=(data&&data.errors&&data.errors.length)?data.errors:[(data&&data.error)?data.error:"Unknown send-test failure."];showResult(false,"Test action failed.",errors);}).catch(function(error){showResult(false,"Test action failed.",[error&&error.message?error.message:"Request failed."]);}).finally(function(){if(sendButton){sendButton.disabled=false;}});});}';
+        echo 'if(form){form.addEventListener("submit",function(ev){var submitter=ev.submitter;if(!submitter||String(submitter.value||"")!=="feca_mailshots_test_send_ui"){return;}ev.preventDefault();var payload=new URLSearchParams(new FormData(form));payload.delete("action");if(sendButton){sendButton.disabled=true;}showResult(true,"Sending test email...",["Rendering PDF attachment and sending message."]);fetch(apiUrl,{method:"POST",credentials:"same-origin",headers:{"Content-Type":"application/x-www-form-urlencoded; charset=UTF-8"},body:payload.toString()}).then(function(response){return response.text().then(function(text){var data=null;try{data=JSON.parse(text);}catch(e){var raw=String(text||"");var snippet="";if(raw){var doc=(new DOMParser()).parseFromString(raw,"text/html");snippet=String((doc&&doc.body&&doc.body.textContent)?doc.body.textContent:raw).split("\n").join(" ").split("\r").join(" ").split("\t").join(" ").trim().slice(0,300);}var msg="Send test failed: server returned HTTP "+response.status+" instead of JSON.";if(snippet){msg+=" Response began: "+snippet;}else{msg+=" Check the WordPress/PHP error log for the underlying fatal error.";}return {ok:false,errors:[msg]};}if(!response.ok&&data&&data.ok!==false){data.ok=false;}return data;});}).then(function(data){if(data&&data.ok){var lines=[];if(data.sent_to){lines.push("Sent to: "+data.sent_to);}if(data.sent_at){lines.push("Sent at: "+data.sent_at);}if(data.warnings&&data.warnings.length){lines=lines.concat(data.warnings.map(function(w){return "Warning: "+w;}));}showResult(true,"Test action succeeded.",lines.length?lines:["Sent."]);return;}var errors=(data&&data.errors&&data.errors.length)?data.errors:[(data&&data.error)?data.error:"Unknown send-test failure."];showResult(false,"Test action failed.",errors);}).catch(function(error){showResult(false,"Test action failed.",[error&&error.message?error.message:"Request failed."]);}).finally(function(){if(sendButton){sendButton.disabled=false;}});});}';
         echo 'window.fecaConfirmTestSend=function(){';
         echo 'var select=document.getElementById("mst_recipient_index");';
         echo 'if(!select){return confirm("Send one test email to the entered address?");}';
@@ -274,10 +312,14 @@ final class MailshotTestAdminPage
         }
 
         $op = (string) ($this->wp->requestParam('op', '') ?? '');
-        $service = $this->runService();
+        $stage = 'initializing test API';
+        $this->registerFatalJsonTrap('test API', $stage);
 
         try {
+            $stage = 'loading run service';
+            $service = $this->runService();
             if ($op === 'default_test_email') {
+                $stage = 'loading default test email';
                 $this->wp->sendJson(['ok' => true] + $service->defaultTestEmail());
                 return;
             }
@@ -286,13 +328,19 @@ final class MailshotTestAdminPage
                 if (!$this->enforceMutationGuardOrJson(self::CAPABILITY, self::NONCE_ACTION)) {
                     return;
                 }
-                $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+                $stage = 'raising memory limit for render test';
+                $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+                if ($memoryError !== null) {
+                    $this->wp->sendJson(['ok' => false, 'errors' => [$memoryError]], 500);
+                    return;
+                }
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
                 $idx = (int) ($this->wp->requestParam('recipient_index', '0') ?? '0');
                 if ($idx < 0) {
                     $this->wp->sendJson(['ok' => false, 'errors' => ['Choose a specific recipient row for Render Test.']]);
                     return;
                 }
+                $stage = 'rendering selected recipient';
                 $this->wp->sendJson($service->renderTest($mailshotId, $idx));
                 return;
             }
@@ -301,21 +349,28 @@ final class MailshotTestAdminPage
                 if (!$this->enforceMutationGuardOrJson(self::CAPABILITY, self::NONCE_ACTION)) {
                     return;
                 }
-                $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+                $stage = 'raising memory limit for send test';
+                $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+                if ($memoryError !== null) {
+                    $this->wp->sendJson(['ok' => false, 'errors' => [$memoryError]], 500);
+                    return;
+                }
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
                 $idx = (int) ($this->wp->requestParam('recipient_index', '0') ?? '0');
                 $to = (string) ($this->wp->requestParam('test_email', '') ?? '');
                 if ($idx < 0) {
+                    $stage = 'sending test email for all recipient rows';
                     $this->wp->sendJson($service->sendTestAll($mailshotId, $to));
                     return;
                 }
+                $stage = 'sending test email for selected recipient';
                 $this->wp->sendJson($service->sendTest($mailshotId, $idx, $to));
                 return;
             }
 
             $this->wp->sendJson(['ok' => false, 'error' => 'Unknown op'], 400);
         } catch (\Throwable $e) {
-            $this->wp->sendJson(['ok' => false, 'error' => $e->getMessage()], 500);
+            $this->wp->sendJson(['ok' => false, 'errors' => [$this->diagnosticError('Test API failed', $stage, $e)]], 500);
         }
     }
 
@@ -330,7 +385,13 @@ final class MailshotTestAdminPage
             $this->redirect($mailshotId, $idx, (string) ($this->wp->requestParam('test_email', '') ?? ''), true);
             return;
         }
-        $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+        $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+        if ($memoryError !== null) {
+            $result = ['ok' => false, 'errors' => [$memoryError], 'ui_action' => 'render'];
+            $this->wp->updateOption(self::RESULT_OPTION_KEY, $result);
+            $this->redirect($mailshotId, $idx, (string) ($this->wp->requestParam('test_email', '') ?? ''));
+            return;
+        }
         $this->redirect($mailshotId, $idx, (string) ($this->wp->requestParam('test_email', '') ?? ''), true);
     }
 
@@ -342,15 +403,21 @@ final class MailshotTestAdminPage
         $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
         $idx = (int) ($this->wp->requestParam('recipient_index', '0') ?? '0');
         $email = (string) ($this->wp->requestParam('test_email', '') ?? '');
+        $stage = 'initializing send test';
         try {
-            $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
-            if ($idx < 0) {
+            $stage = 'raising memory limit for send test';
+            $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+            if ($memoryError !== null) {
+                $result = ['ok' => false, 'errors' => [$memoryError]];
+            } elseif ($idx < 0) {
+                $stage = 'sending test email for all recipient rows';
                 $result = $this->runService()->sendTestAll($mailshotId, $email);
             } else {
+                $stage = 'sending test email for selected recipient';
                 $result = $this->runService()->sendTest($mailshotId, $idx, $email);
             }
         } catch (\Throwable $e) {
-            $result = ['ok' => false, 'errors' => ['Send test failed: ' . $e->getMessage()]];
+            $result = ['ok' => false, 'errors' => [$this->diagnosticError('Send test failed', $stage, $e)]];
         }
         unset($result['rendered']);
         $result['ui_action'] = 'send';
@@ -378,10 +445,10 @@ final class MailshotTestAdminPage
         return is_array($raw) ? $raw : null;
     }
 
-    private function maybeRaiseMemoryLimit(string $target): void
+    private function maybeRaiseMemoryLimit(string $target): ?string
     {
         if ($target === '' || !function_exists('ini_get') || !function_exists('ini_set')) {
-            return;
+            return null;
         }
 
         $current = (string) ini_get('memory_limit');
@@ -389,10 +456,17 @@ final class MailshotTestAdminPage
         $targetBytes = $this->memoryLimitToBytes($target);
 
         if ($currentBytes < 0 || $targetBytes <= 0 || $currentBytes >= $targetBytes) {
-            return;
+            return null;
         }
 
         @ini_set('memory_limit', $target);
+        $new = (string) ini_get('memory_limit');
+        $newBytes = $this->memoryLimitToBytes($new);
+        if ($newBytes >= $targetBytes || $newBytes < 0) {
+            return null;
+        }
+
+        return 'Mailshot Test needs PHP memory_limit ' . $target . ' for this action, but the server is still using ' . $new . '. Increase the FECA Mailshots Setup memory limit or the hosting PHP memory_limit before retrying.';
     }
 
     private function resolveDownloadMemoryLimitTarget(): string
@@ -413,7 +487,7 @@ final class MailshotTestAdminPage
             }
         }
 
-        return '';
+        return self::DEFAULT_DOWNLOAD_MEMORY_LIMIT;
     }
 
     private function memoryLimitToBytes(string $limit): int
@@ -444,6 +518,54 @@ final class MailshotTestAdminPage
         return (int) $value;
     }
 
+    private function registerFatalJsonTrap(string $context, string &$stage): void
+    {
+        if (!function_exists('register_shutdown_function')) {
+            return;
+        }
+
+        register_shutdown_function(function () use ($context, &$stage): void {
+            $error = error_get_last();
+            if (!is_array($error)) {
+                return;
+            }
+            $type = (int) ($error['type'] ?? 0);
+            if (!in_array($type, [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR, E_RECOVERABLE_ERROR], true)) {
+                return;
+            }
+
+            $message = trim((string) ($error['message'] ?? 'Unknown fatal error.'));
+            $file = basename((string) ($error['file'] ?? 'unknown'));
+            $line = (int) ($error['line'] ?? 0);
+            $payload = [
+                'ok' => false,
+                'errors' => [
+                    'Mailshots ' . $context . ' fatal error during ' . $stage . ': ' . $message . ' [' . $file . ':' . $line . ']',
+                ],
+            ];
+            if (!headers_sent()) {
+                if (function_exists('status_header')) {
+                    status_header(500);
+                } else {
+                    http_response_code(500);
+                }
+                header('Content-Type: application/json; charset=UTF-8');
+            }
+            echo json_encode($payload, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
+        });
+    }
+
+    private function diagnosticError(string $prefix, string $stage, \Throwable $e): string
+    {
+        $message = $prefix . ' during ' . $stage . ': ' . $e->getMessage();
+        $file = $e->getFile();
+        $line = $e->getLine();
+        if ($file !== '' && $line > 0) {
+            $message .= ' [' . get_class($e) . ' at ' . basename($file) . ':' . $line . ']';
+        }
+        return $message;
+    }
+
     private function runService(): MailshotRunService
     {
         return ($this->runServiceFactory)();
diff --git a/feca_mailshots_plugin/src/Admin/RunMailshotAdminPage.php b/feca_mailshots_plugin/src/Admin/RunMailshotAdminPage.php
index afb7cdc..49ac12a 100644
--- a/feca_mailshots_plugin/src/Admin/RunMailshotAdminPage.php
+++ b/feca_mailshots_plugin/src/Admin/RunMailshotAdminPage.php
@@ -15,6 +15,9 @@ final class RunMailshotAdminPage
     private const RESULT_OPTION_KEY = 'feca_mailshots_run_ui_result';
     private const CAPABILITY = 'edit_pages';
     private const NONCE_ACTION = 'feca_mailshots_run';
+    private const DOWNLOAD_MEMORY_LIMIT_ENV = 'FECA_MAILSHOTS_DOWNLOAD_MEMORY_LIMIT';
+    private const DOWNLOAD_MEMORY_LIMIT_OPTION = 'feca_mailshots_download_memory_limit';
+    private const DEFAULT_DOWNLOAD_MEMORY_LIMIT = '512M';
 
     /** @var callable(): MailshotRunService */
     private $runServiceFactory;
@@ -54,15 +57,34 @@ final class RunMailshotAdminPage
             return;
         }
 
-        $mailshots = $this->mailshotService()->list();
+        $pageErrors = [];
+        $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+        if ($memoryError !== null) {
+            $pageErrors[] = $memoryError;
+        }
+        try {
+            $mailshots = $this->mailshotService()->list();
+        } catch (\Throwable $e) {
+            $mailshots = [];
+            $pageErrors[] = $this->diagnosticError('Unable to load mailshots', 'loading run page', $e);
+        }
         $selectedMailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
         if ($selectedMailshotId <= 0 && $mailshots !== []) {
             $selectedMailshotId = (int) ($mailshots[0]['id'] ?? 0);
         }
 
         $result = $this->result();
-        $lastRunRows = $selectedMailshotId > 0 ? $this->mailshotService()->lastRun($selectedMailshotId) : [];
-        $recipientSummary = $selectedMailshotId > 0 ? $this->runService()->recipientCount($selectedMailshotId) : ['ok' => false, 'errors' => ['No mailshot selected.']];
+        try {
+            $lastRunRows = $selectedMailshotId > 0 ? $this->mailshotService()->lastRun($selectedMailshotId) : [];
+        } catch (\Throwable $e) {
+            $lastRunRows = [];
+            $pageErrors[] = $this->diagnosticError('Unable to load last-run rows', 'loading run page', $e);
+        }
+        try {
+            $recipientSummary = $selectedMailshotId > 0 ? $this->runService()->recipientCount($selectedMailshotId) : ['ok' => false, 'errors' => ['No mailshot selected.']];
+        } catch (\Throwable $e) {
+            $recipientSummary = ['ok' => false, 'errors' => [$this->diagnosticError('Recipient count failed', 'loading run page', $e)]];
+        }
         $runCount = !empty($recipientSummary['ok']) ? (int) ($recipientSummary['count'] ?? 0) : 0;
         $action = htmlspecialchars($this->wp->adminUrl('admin-post.php'));
 
@@ -70,6 +92,14 @@ final class RunMailshotAdminPage
         echo $this->renderAdminUiStyles();
         echo '<p>Execute full sends and retry failures from the current mailshot last-run rows.</p>';
 
+        if ($pageErrors !== []) {
+            echo '<div class="feca-banner feca-banner-error"><strong>Run page diagnostics</strong>';
+            foreach ($pageErrors as $pageError) {
+                echo '<p class="feca-banner-note">' . htmlspecialchars($pageError, ENT_QUOTES) . '</p>';
+            }
+            echo '</div>';
+        }
+
         if ($result !== null) {
             $ok = !empty($result['ok']);
             $bannerClass = $ok ? 'feca-banner-success' : 'feca-banner-error';
@@ -191,11 +221,21 @@ final class RunMailshotAdminPage
         }
 
         $op = (string) ($this->wp->requestParam('op', '') ?? '');
-        $service = $this->runService();
+        $stage = 'initializing run API';
+        $this->registerFatalJsonTrap('run API', $stage);
 
         try {
+            $stage = 'raising memory limit for run action';
+            $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+            if ($memoryError !== null) {
+                $this->wp->sendJson(['ok' => false, 'errors' => [$memoryError]], 500);
+                return;
+            }
+            $stage = 'loading run service';
+            $service = $this->runService();
             if ($op === 'run_mailshot') {
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
+                $stage = 'running mailshot';
                 $this->wp->sendJson($service->runMailshot($mailshotId));
                 return;
             }
@@ -203,12 +243,14 @@ final class RunMailshotAdminPage
             if ($op === 'run_mailshot_selected') {
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
                 $selectedRecipientKeys = $this->selectedRecipientKeysFromRequest();
+                $stage = 'running selected recipient rows';
                 $this->wp->sendJson($service->runMailshotSelected($mailshotId, $selectedRecipientKeys));
                 return;
             }
 
             if ($op === 'retry_failed') {
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
+                $stage = 'retrying failed recipients';
                 $this->wp->sendJson($service->retryFailed($mailshotId));
                 return;
             }
@@ -216,13 +258,14 @@ final class RunMailshotAdminPage
             if ($op === 'retry_recipient') {
                 $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
                 $recipientKey = (string) ($this->wp->requestParam('recipient_key', '') ?? '');
+                $stage = 'retrying one recipient';
                 $this->wp->sendJson($service->retryRecipient($mailshotId, $recipientKey));
                 return;
             }
 
             $this->wp->sendJson(['ok' => false, 'error' => 'Unknown op'], 400);
         } catch (\Throwable $e) {
-            $this->wp->sendJson(['ok' => false, 'error' => $e->getMessage()], 500);
+            $this->wp->sendJson(['ok' => false, 'errors' => [$this->diagnosticError('Run API failed', $stage, $e)]], 500);
         }
     }
 
@@ -269,8 +312,9 @@ final class RunMailshotAdminPage
         $mailshotId = (int) ($this->wp->requestParam('mailshot_id', '0') ?? '0');
         $completed = false;
         $fatalHandled = false;
+        $stage = 'initializing run action';
 
-        register_shutdown_function(function () use (&$completed, &$fatalHandled, $mailshotId): void {
+        register_shutdown_function(function () use (&$completed, &$fatalHandled, $mailshotId, &$stage): void {
             if ($completed || $fatalHandled) {
                 return;
             }
@@ -279,14 +323,23 @@ final class RunMailshotAdminPage
                 return;
             }
             $fatalHandled = true;
-            $this->storeRunFailure('Run action failed: ' . (string) ($error['message'] ?? 'Unknown fatal error.'));
+            $file = basename((string) ($error['file'] ?? 'unknown'));
+            $line = (int) ($error['line'] ?? 0);
+            $this->storeRunFailure('Run action fatal error during ' . $stage . ': ' . (string) ($error['message'] ?? 'Unknown fatal error.') . ' [' . $file . ':' . $line . ']');
             $this->redirect($mailshotId);
         });
 
         try {
-            $result = $action($this, $mailshotId);
+            $stage = 'raising memory limit for run action';
+            $memoryError = $this->maybeRaiseMemoryLimit($this->resolveDownloadMemoryLimitTarget());
+            if ($memoryError !== null) {
+                $result = ['ok' => false, 'errors' => [$memoryError]];
+            } else {
+                $stage = 'executing run action';
+                $result = $action($this, $mailshotId);
+            }
         } catch (\Throwable $e) {
-            $result = ['ok' => false, 'errors' => ['Run action failed: ' . $e->getMessage()]];
+            $result = ['ok' => false, 'errors' => [$this->diagnosticError('Run action failed', $stage, $e)]];
         }
 
         $completed = true;
@@ -330,6 +383,127 @@ final class RunMailshotAdminPage
         return ($this->mailshotServiceFactory)();
     }
 
+    private function maybeRaiseMemoryLimit(string $target): ?string
+    {
+        if ($target === '' || !function_exists('ini_get') || !function_exists('ini_set')) {
+            return null;
+        }
+
+        $current = (string) ini_get('memory_limit');
+        $currentBytes = $this->memoryLimitToBytes($current);
+        $targetBytes = $this->memoryLimitToBytes($target);
+
+        if ($currentBytes < 0 || $targetBytes <= 0 || $currentBytes >= $targetBytes) {
+            return null;
+        }
+
+        @ini_set('memory_limit', $target);
+        $new = (string) ini_get('memory_limit');
+        $newBytes = $this->memoryLimitToBytes($new);
+        if ($newBytes >= $targetBytes || $newBytes < 0) {
+            return null;
+        }
+
+        return 'Run Mailshot needs PHP memory_limit ' . $target . ' for this action, but the server is still using ' . $new . '. Increase the FECA Mailshots Setup memory limit or the hosting PHP memory_limit before retrying.';
+    }
+
+    private function resolveDownloadMemoryLimitTarget(): string
+    {
+        $optionValue = $this->wp->getOption(self::DOWNLOAD_MEMORY_LIMIT_OPTION, '');
+        if (is_string($optionValue)) {
+            $value = trim($optionValue);
+            if ($this->memoryLimitToBytes($value) > 0) {
+                return $value;
+            }
+        }
+
+        $envValue = getenv(self::DOWNLOAD_MEMORY_LIMIT_ENV);
+        if (is_string($envValue)) {
+            $value = trim($envValue);
+            if ($this->memoryLimitToBytes($value) > 0) {
+                return $value;
+            }
+        }
+
+        return self::DEFAULT_DOWNLOAD_MEMORY_LIMIT;
+    }
+
+    private function memoryLimitToBytes(string $limit): int
+    {
+        $value = trim($limit);
+        if ($value === '') {
+            return 0;
+        }
+        if ($value === '-1') {
+            return -1;
+        }
+
+        $unit = strtolower(substr($value, -1));
+        if (ctype_alpha($unit)) {
+            $number = (float) substr($value, 0, -1);
+            switch ($unit) {
+                case 'g':
+                    return (int) ($number * 1024 * 1024 * 1024);
+                case 'm':
+                    return (int) ($number * 1024 * 1024);
+                case 'k':
+                    return (int) ($number * 1024);
+                default:
+                    return (int) $number;
+            }
+        }
+
+        return (int) $value;
+    }
+
+    private function registerFatalJsonTrap(string $context, string &$stage): void
+    {
+        if (!function_exists('register_shutdown_function')) {
+            return;
+        }
+
+        register_shutdown_function(function () use ($context, &$stage): void {
+            $error = error_get_last();
+            if (!is_array($error)) {
+                return;
+            }
+            $type = (int) ($error['type'] ?? 0);
+            if (!in_array($type, [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR, E_RECOVERABLE_ERROR], true)) {
+                return;
+            }
+
+            $message = trim((string) ($error['message'] ?? 'Unknown fatal error.'));
+            $file = basename((string) ($error['file'] ?? 'unknown'));
+            $line = (int) ($error['line'] ?? 0);
+            $payload = [
+                'ok' => false,
+                'errors' => [
+                    'Mailshots ' . $context . ' fatal error during ' . $stage . ': ' . $message . ' [' . $file . ':' . $line . ']',
+                ],
+            ];
+            if (!headers_sent()) {
+                if (function_exists('status_header')) {
+                    status_header(500);
+                } else {
+                    http_response_code(500);
+                }
+                header('Content-Type: application/json; charset=UTF-8');
+            }
+            echo json_encode($payload, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
+        });
+    }
+
+    private function diagnosticError(string $prefix, string $stage, \Throwable $e): string
+    {
+        $message = $prefix . ' during ' . $stage . ': ' . $e->getMessage();
+        $file = $e->getFile();
+        $line = $e->getLine();
+        if ($file !== '' && $line > 0) {
+            $message .= ' [' . get_class($e) . ' at ' . basename($file) . ':' . $line . ']';
+        }
+        return $message;
+    }
+
     /** @param list<array<string,mixed>> $mailshots */
     private function selectedMailshotDataSource(array $mailshots, int $mailshotId): string
     {
diff --git a/feca_mailshots_plugin/src/Admin/SetupAdminPage.php b/feca_mailshots_plugin/src/Admin/SetupAdminPage.php
index 8aeb96f..a6f879e 100644
--- a/feca_mailshots_plugin/src/Admin/SetupAdminPage.php
+++ b/feca_mailshots_plugin/src/Admin/SetupAdminPage.php
@@ -99,11 +99,11 @@ final class SetupAdminPage
         $this->field('Members DB Name', 'members_db_name', $saved['members_db_name'] ?? '');
         $this->field('FEN DB Name', 'fen_db_name', $saved['fen_db_name'] ?? '');
         $this->field(
-            'Download PDF Memory Limit',
+            'PDF/Test Memory Limit',
             'download_memory_limit',
             $downloadMemoryLimit,
             'text',
-            'PHP memory_limit value used for Download PDF actions (for example: 256M, 512M, 1G). Suggested value 512M.'
+            'PHP memory_limit value used for Download PDF and Mailshot Test actions (for example: 256M, 512M, 1G). Suggested value 512M.'
         );
         echo '</table>';
 
diff --git a/feca_mailshots_plugin/src/Application/MailshotRunService.php b/feca_mailshots_plugin/src/Application/MailshotRunService.php
index 8c8fc86..5875966 100644
--- a/feca_mailshots_plugin/src/Application/MailshotRunService.php
+++ b/feca_mailshots_plugin/src/Application/MailshotRunService.php
@@ -138,22 +138,27 @@ final class MailshotRunService
             return ['ok' => false, 'errors' => ['Test email address is required.']];
         }
 
+        $stage = 'initializing send test';
         try {
+            $stage = 'loading mail credentials';
             $creds = $this->credentials->credentials();
             if ($creds === null) {
                 return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
             }
 
+            $stage = 'rendering selected recipient';
             $render = $this->renderTest($mailshotId, $recipientIndex);
             if (($render['ok'] ?? false) !== true) {
                 return $render;
             }
 
+            $stage = 'loading mailshot definition';
             $mailshot = $this->mailshots->find($mailshotId);
             if ($mailshot === null) {
                 return ['ok' => false, 'errors' => ['Mailshot not found.']];
             }
 
+            $stage = 'preparing recipients and attachments';
             $cc = $this->splitAddresses((string) ($mailshot['CC'] ?? ''));
             $bcc = $this->splitAddresses((string) ($mailshot['BCC'] ?? ''));
             $attachments = array_merge(
@@ -163,6 +168,7 @@ final class MailshotRunService
 
             $attemptId = 'test_' . $mailshotId . '_' . $recipientIndex . '_' . gmdate('YmdHis');
 
+            $stage = 'sending SMTP message';
             $send = $this->smtp->send(
                 $creds,
                 [$testEmail],
@@ -175,6 +181,7 @@ final class MailshotRunService
             );
             $warnings = [];
             try {
+                $stage = 'appending IMAP sent copy';
                 $this->imap->appendSent($creds, (string) $send['raw_mime'], $attemptId);
             } catch (\Throwable $e) {
                 $warnings[] = 'IMAP sent-copy failed: ' . $e->getMessage();
@@ -187,7 +194,7 @@ final class MailshotRunService
                 'sent_at' => gmdate('c'),
             ];
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Send test failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Send test failed', $stage, $e)]];
         }
     }
 
@@ -199,17 +206,21 @@ final class MailshotRunService
             return ['ok' => false, 'errors' => ['Test email address is required.']];
         }
 
+        $stage = 'initializing send-all test';
         try {
+            $stage = 'loading mail credentials';
             $creds = $this->credentials->credentials();
             if ($creds === null) {
                 return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
             }
 
+            $stage = 'loading recipients';
             [$mailshot, $rows] = $this->loadMailshotAndRows($mailshotId);
             if ($rows === []) {
                 return ['ok' => false, 'errors' => ['Recipient query returned zero rows.']];
             }
 
+            $stage = 'preparing mailshot addresses';
             $cc = $this->splitAddresses((string) ($mailshot['CC'] ?? ''));
             $bcc = $this->splitAddresses((string) ($mailshot['BCC'] ?? ''));
             $counters = ['attempted' => 0, 'sent' => 0, 'failed' => 0, 'warnings' => 0];
@@ -219,16 +230,19 @@ final class MailshotRunService
                 $counters['attempted']++;
                 [$recipientKeyField, $recipientKey] = $this->detectRecipientKey((array) $row, $index);
                 try {
+                    $rowStage = 'rendering template';
                     $render = $this->renderer->render(
                         (string) $mailshot['Subject'],
                         (string) $mailshot['Message'],
                         (string) ($mailshot['PDFAttachment'] ?? ''),
                         (array) $row
                     );
+                    $rowStage = 'preparing attachments';
                     $attachments = array_merge(
                         $this->staticAttachments($mailshot),
                         $this->renderedPdfAttachments($mailshot, (array) $row, $render)
                     );
+                    $rowStage = 'sending SMTP message';
                     $send = $this->smtp->send(
                         $creds,
                         [$testEmail],
@@ -248,7 +262,7 @@ final class MailshotRunService
                     }
                 } catch (\Throwable $e) {
                     $counters['failed']++;
-                    $errors[] = 'Recipient ' . $recipientKeyField . '=' . $recipientKey . ': ' . $e->getMessage();
+                    $errors[] = 'Recipient ' . $recipientKeyField . '=' . $recipientKey . ' failed during ' . $rowStage . ': ' . $e->getMessage();
                 }
             }
 
@@ -258,70 +272,92 @@ final class MailshotRunService
                 'sent_at' => gmdate('c'),
             ] + $counters + ['errors' => $errors];
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Send test failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Send test failed', $stage, $e)]];
         }
     }
 
+    private function diagnosticError(string $prefix, string $stage, \Throwable $e): string
+    {
+        $message = $prefix . ' during ' . $stage . ': ' . $e->getMessage();
+        $file = $e->getFile();
+        $line = $e->getLine();
+        if ($file !== '' && $line > 0) {
+            $message .= ' [' . get_class($e) . ' at ' . basename($file) . ':' . $line . ']';
+        }
+        return $message;
+    }
+
     /** @return array<string, mixed> */
     public function runMailshot(int $mailshotId): array
     {
+        $stage = 'initializing full run';
         try {
-            return $this->runMailshotUnsafe($mailshotId);
+            return $this->runMailshotUnsafe($mailshotId, $stage);
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Run mailshot failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Run mailshot failed', $stage, $e)]];
         }
     }
 
     /** @return array<string, mixed> */
-    private function runMailshotUnsafe(int $mailshotId): array
+    private function runMailshotUnsafe(int $mailshotId, string &$stage): array
     {
+        $stage = 'loading mailshot definition';
         $mailshot = $this->mailshots->find($mailshotId);
         if ($mailshot === null) {
             return ['ok' => false, 'errors' => ['Mailshot not found.']];
         }
 
+        $stage = 'loading mail credentials';
         $creds = $this->credentials->credentials();
         if ($creds === null) {
             return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
         }
 
+        $stage = 'loading recipient rows';
         [$mailshot, $rows] = $this->loadMailshotAndRows($mailshotId);
         if ($rows === []) {
             return ['ok' => false, 'errors' => ['Recipient query returned zero rows.']];
         }
 
+        $stage = 'clearing previous run rows';
         $this->lastRun->clearForMailshot($mailshotId);
+        $stage = 'sending recipient rows';
         return $this->executeSendLoop($mailshotId, $mailshot, $rows, $creds, true);
     }
 
     /** @param list<string> $selectedRecipientKeys @return array<string, mixed> */
     public function runMailshotSelected(int $mailshotId, array $selectedRecipientKeys): array
     {
+        $stage = 'initializing selected run';
         try {
-            return $this->runMailshotSelectedUnsafe($mailshotId, $selectedRecipientKeys);
+            return $this->runMailshotSelectedUnsafe($mailshotId, $selectedRecipientKeys, $stage);
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Run selected mailshot failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Run selected mailshot failed', $stage, $e)]];
         }
     }
 
     /** @param list<string> $selectedRecipientKeys @return array<string, mixed> */
-    private function runMailshotSelectedUnsafe(int $mailshotId, array $selectedRecipientKeys): array
+    private function runMailshotSelectedUnsafe(int $mailshotId, array $selectedRecipientKeys, string &$stage): array
     {
+        $stage = 'validating selected recipient rows';
         $selectedRecipientKeys = array_values(array_filter(array_map(static fn($v): string => trim((string) $v), $selectedRecipientKeys), static fn(string $v): bool => $v !== ''));
         if ($selectedRecipientKeys === []) {
             return ['ok' => false, 'errors' => ['No selected recipient rows were provided.']];
         }
 
+        $stage = 'loading mail credentials';
         $creds = $this->credentials->credentials();
         if ($creds === null) {
             return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
         }
 
+        $stage = 'loading recipient rows';
         [$mailshot, $rows] = $this->loadMailshotAndRows($mailshotId);
         if ($rows === []) {
             return ['ok' => false, 'errors' => ['Recipient query returned zero rows.']];
         }
 
+        $stage = 'matching selected recipient rows';
         $selectedSet = array_fill_keys($selectedRecipientKeys, true);
         $filteredRows = [];
         foreach (array_values($rows) as $index => $row) {
@@ -335,7 +371,9 @@ final class MailshotRunService
             return ['ok' => false, 'errors' => ['None of the selected recipient rows exist in the current query result.']];
         }
 
+        $stage = 'clearing previous run rows';
         $this->lastRun->clearForMailshot($mailshotId);
+        $stage = 'sending selected recipient rows';
         $result = $this->executeSendLoop($mailshotId, $mailshot, $filteredRows, $creds, true);
         $result['selected_count'] = count($filteredRows);
         return $result;
@@ -344,28 +382,33 @@ final class MailshotRunService
     /** @return array<string, mixed> */
     public function retryFailed(int $mailshotId): array
     {
+        $stage = 'initializing retry failed';
         try {
-            return $this->retryFailedUnsafe($mailshotId);
+            return $this->retryFailedUnsafe($mailshotId, $stage);
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Retry failed sends failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Retry failed sends failed', $stage, $e)]];
         }
     }
 
     /** @return array<string, mixed> */
-    private function retryFailedUnsafe(int $mailshotId): array
+    private function retryFailedUnsafe(int $mailshotId, string &$stage): array
     {
+        $stage = 'loading mail credentials';
         $creds = $this->credentials->credentials();
         if ($creds === null) {
             return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
         }
 
+        $stage = 'loading recipient rows';
         [$mailshot, $rows] = $this->loadMailshotAndRows($mailshotId);
+        $stage = 'loading failed last-run rows';
         $failed = array_values(array_filter($this->lastRun->listForMailshot($mailshotId), static fn(array $r): bool => (string) ($r['status'] ?? '') === 'failed'));
 
         if ($failed === []) {
             return ['ok' => true, 'attempted' => 0, 'sent' => 0, 'failed' => 0, 'warnings' => 0, 'log' => []];
         }
 
+        $stage = 'matching failed recipient rows';
         $retryRows = [];
         foreach ($failed as $f) {
             $keyField = (string) ($f['recipient_key_field'] ?? '');
@@ -376,33 +419,39 @@ final class MailshotRunService
             }
         }
 
+        $stage = 'sending failed recipient rows';
         return $this->executeSendLoop($mailshotId, $mailshot, $retryRows, $creds, false);
     }
 
     /** @return array<string, mixed> */
     public function retryRecipient(int $mailshotId, string $recipientKey): array
     {
+        $stage = 'initializing recipient retry';
         try {
-            return $this->retryRecipientUnsafe($mailshotId, $recipientKey);
+            return $this->retryRecipientUnsafe($mailshotId, $recipientKey, $stage);
         } catch (\Throwable $e) {
-            return ['ok' => false, 'errors' => ['Retry recipient failed: ' . $e->getMessage()]];
+            return ['ok' => false, 'errors' => [$this->diagnosticError('Retry recipient failed', $stage, $e)]];
         }
     }
 
     /** @return array<string, mixed> */
-    private function retryRecipientUnsafe(int $mailshotId, string $recipientKey): array
+    private function retryRecipientUnsafe(int $mailshotId, string $recipientKey, string &$stage): array
     {
+        $stage = 'validating recipient retry request';
         $recipientKey = trim($recipientKey);
         if ($recipientKey === '') {
             return ['ok' => false, 'errors' => ['recipient_key is required.']];
         }
 
+        $stage = 'loading mail credentials';
         $creds = $this->credentials->credentials();
         if ($creds === null) {
             return ['ok' => false, 'errors' => ['Missing mail credentials. Configure FECA Mailshots Profile page first.']];
         }
 
+        $stage = 'loading recipient rows';
         [$mailshot, $rows] = $this->loadMailshotAndRows($mailshotId);
+        $stage = 'loading last-run rows';
         $entries = $this->lastRun->listForMailshot($mailshotId);
         $candidate = null;
         foreach ($entries as $e) {
@@ -415,11 +464,13 @@ final class MailshotRunService
             return ['ok' => false, 'errors' => ['No last-run row found for recipient_key.']];
         }
 
+        $stage = 'matching recipient row';
         $row = $this->findRecipientByKey($rows, (string) ($candidate['recipient_key_field'] ?? ''), $recipientKey);
         if ($row === null) {
             return ['ok' => false, 'errors' => ['Recipient not found in current data source result.']];
         }
 
+        $stage = 'sending recipient retry';
         return $this->executeSendLoop($mailshotId, $mailshot, [$row], $creds, false);
     }
 
@@ -758,6 +809,7 @@ final class MailshotRunService
      */
     private function executeSendLoop(int $mailshotId, array $mailshot, array $rows, array $creds, bool $freshRun): array
     {
+        $stage = 'preparing mailshot addresses';
         $cc = $this->splitAddresses((string) ($mailshot['CC'] ?? ''));
         $bcc = $this->splitAddresses((string) ($mailshot['BCC'] ?? ''));
         $recipientEmailField = trim((string) ($mailshot['RecipientEmailField'] ?? ''));
@@ -766,6 +818,7 @@ final class MailshotRunService
         $log = [];
 
         foreach (array_values($rows) as $index => $row) {
+            $stage = 'detecting recipient address';
             $counters['attempted']++;
             $recipientEmail = $this->detectEmail($row, $recipientEmailField);
             [$recipientKeyField, $recipientKey] = $this->detectRecipientKey($row, $index);
@@ -789,6 +842,7 @@ final class MailshotRunService
             }
 
             try {
+                $stage = 'rendering template for recipient ' . $recipientKey;
                 $render = $this->renderer->render(
                     (string) $mailshot['Subject'],
                     (string) $mailshot['Message'],
@@ -813,10 +867,12 @@ final class MailshotRunService
             }
 
             try {
+                $stage = 'preparing attachments for recipient ' . $recipientKey;
                 $attachments = array_merge(
                     $this->staticAttachments($mailshot),
                     $this->renderedPdfAttachments($mailshot, $row, $render)
                 );
+                $stage = 'sending SMTP message for recipient ' . $recipientKey;
                 $smtp = $this->smtp->send(
                     $creds,
                     [$recipientEmail],
@@ -830,6 +886,7 @@ final class MailshotRunService
 
                 $warning = null;
                 try {
+                    $stage = 'appending IMAP sent copy for recipient ' . $recipientKey;
                     $attemptId = sprintf('run_%d_%s_%d', $mailshotId, $recipientKey, time());
                     $this->imap->appendSent($creds, (string) $smtp['raw_mime'], $attemptId);
                 } catch (\Throwable $imapErr) {
@@ -853,7 +910,8 @@ final class MailshotRunService
                 ]);
             } catch (\Throwable $e) {
                 $counters['failed']++;
-                $log[] = ['recipient_key' => $recipientKey, 'status' => 'failed', 'error' => $e->getMessage()];
+                $error = $this->diagnosticError('Recipient send failed', $stage, $e);
+                $log[] = ['recipient_key' => $recipientKey, 'status' => 'failed', 'error' => $error];
                 $this->lastRun->create([
                     'mailshot_id' => $mailshotId,
                     'data_source' => (string) ($mailshot['DataSource'] ?? ''),
@@ -862,7 +920,7 @@ final class MailshotRunService
                     'recipient_key_field' => $recipientKeyField,
                     'recipient_email_last' => $recipientEmail,
                     'status' => 'failed',
-                    'error_message' => $e->getMessage(),
+                    'error_message' => $error,
                     'attempt_count' => $freshRun ? 1 : 2,
                 ]);
             }
diff --git a/results/manual-testing-1.md b/results/manual-testing-1.md
index d1ff8c7..651d200 100644
--- a/results/manual-testing-1.md
+++ b/results/manual-testing-1.md
@@ -26,4 +26,6 @@
 * [X] Mailshot data sources.  Add "Duplicate" button per row.
 * [X] Select a single row in "review recipients".   "Run Mailshot to selected rows" says "Run mailshot to 1 selected rows?".  Yes -> error "None of the selected recipient rows exist in the current query result."
 * [X] Error report from wordpress. - packaging was missing a file
-* [ ] Subject to "Memory box café generates an error from receiveing yahoo email "subject contains an invalid character".   Need to check rules for character set in subject and modify special characters accordingly.
+* [ ] Subject to "Memory box café generates an error from receiveing yahoo email "subject contains an invalid character".   Need to check rules for character set in subject and modify special characters accordingly.  Problem characters include quote (All Saint's) and e accent (café).
+* [ ] (patch 32, 33) Test email including these characters critical errors wordpress.  Perhaps because "Last Run Rows" was non-empty and related to a previous different mailshot / data source.   Still critical errors after attempt to make more robust.
+* [ ] patch 30 also criticals sending to "test" mailshot,  but OK sending to fen contacts.