Mail Queues

The diagnosis "Mail Queue" checks the number of e-mails in the SMTP incoming and outgoing queues.

Check whether there are errors in the mail flow.
For outgoing mail queues, this could be due to inaccessible internal mail servers.
In the case of a mail jam in the incoming SMTP queue, the cause could be a spam attack, or processing difficulties due to an excessive number of RBL blacklist servers or timeouts when checking the blacklist servers.