Messages from some or all sources are delayed or fail to be delivered. When searching the Message Audit Logs for the sending IP via the Control Center Status > Message Audit Logs you find:
The "Sender abort message" action is logged when the sender quit the SMTP session before delivering the full message.
If you need to engage Broadcom support to assist in investigating the issue, please collect the following information in order to facilitate the investigation:
For "Abort message" action, see the article Some messages show "Abort message" in SMG's audit logs.