Deferred mail in CARBONIO queue

Hi guys!

3 weeks ago I moved from Zimbra to Carbonio.

Until now everything was fine.
Today I saw few deferred mails in the queue.

mailq:

connect to 127.0.0.1[127.0.0.1]:10024: Connection refused

I looks like Amavis did not work.
After restart all stack of Carbonio services it didn't change.

After restart of the sever it work.

What could be the root cause of this problem?

Kind regards,

Plamen_F