Our Zimbra mail server (Open shourse Edition 8.0.3 ) often face problem to receive large email (~5MB), especially from google mail server.
We upgraded the server hardware, so performance wise should be more than enough.
We thought is problem is due to internet line, we upgrade the internet connection as well, but still facing the same issue, connection timeout.

Sep 17 09:29:43 mail postfix/smtpd[15994]: timeout after DATA (139955 bytes) from mail-wg0-f51.google.com[74.125.82.51]
Sep 17 09:29:44 mail postfix/smtpd[15994]: disconnect from mail-wg0-f51.google.com[74.125.82.51]

Any suggestion on configuration that I can adjust?