Fatal error: Uncaught Error: Class 'Swift_Mime_Headers_AbstractHeader' not found in /home/httpsrejanstsapp/public_html/protected/extensions/yii-mail/vendors/swiftMailer/classes/Swift/Mime/Headers/UnstructuredHeader.php:21 Stack trace: #0 {main} thrown in /home/httpsrejanstsapp/public_html/protected/extensions/yii-mail/vendors/swiftMailer/classes/Swift/Mime/Headers/UnstructuredHeader.php on line 21