- Swift_TransportException: Email to @.*** failed: Expected response code 250 but got code "451", with message "451-Requested action aborted 451 Mails per session limit exceeded. "
- src/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php:457
Since some days this seems to happen very often every day. May someone tell me, what this means, please?