Troubleshoot and resolve The sender's email address is not registered. (WHMCS 8.4 and later) or Unregistered Email Address (WHMCS 8.3 and earlier) errors.
Troubleshoot and resolve issues with sending general emails to clients.
Troubleshoot and resolve issues with ticket notification emails.
Troubleshoot and resolve issues with welcome emails not sending.
Troubleshoot and resolve Unsupported Protocol errors.
Troubleshoot and resolve Apply update dry-run detected permission issues errors.
Troubleshoot and resolve Update Failed errors.