Since yesterday I have a problem with Zimbra. Part of the incoming message passes through the server, and part of it is in line with the message "lost connection with domain [ip] while sending end of data - message may be sent more than once"

I tried to disable anti-virus / anti-spam but messages in the queue after taking postqueue-f on locally can not be delivered. Some new messages are passing clearly.

Does anyone have any idea what might be the cause?