Package and individual mail sender, new report, and other changes

Co-authored-by: Copilot <copilot@github.com>

app/Http/Requests/UpdateMailProfileRequest.php

@@ -27,6 +27,8 @@ public function rules(): array
             'priority' => ['nullable', 'integer', 'between:0,65535'],
             'max_daily_quota' => ['nullable', 'integer', 'min:0'],
             'active' => ['nullable', 'boolean'],
+            'signature' => ['nullable', 'array'],
+            'signature.*' => ['nullable', 'string', 'max:1000'],
         ];
     }
 }