- MailEnable mail queue is big.
- Emails are delivered with delay.
- Messages are stuck in SMTP inbound queue.
- Restarting the MTA service causes the queues to be processed again.
- MailEnable version is 8.x.
Outdated version of MailEnable.
Upgrade MailEnable to the latest supported version using the article How to upgrade MailEnable to a newer version.