We are running a Zimbra mail server on a Linux platform from behind a firewall.
SMTP and DNS ports are open on the firewall along with correct setting on the external DNS (hosted by the ISP) for forward and reverse lookups.
Inbound mail seems to be arriving fine.
Most of the outbound email is being sent the rest is being deferred, test messages sent to my gmail seem to arrive without any problems.
errors in the /var/log.zimbra.log as follows;
- deferred (lost connection with mx2.hotmail.com[22.214.171.124] while sending message body)
- (lost connection with mail.domain.org.nz[126.96.36.199] while sending end of data -- message may be sent more than once)
- deferred (host mx2.securemx.biz[188.8.131.52] said: 421 4.4.2 service timed out. (in reply to end of DATA command))
- deferred (host mail.domain.co.nz[184.108.40.206] said: 451 4.7.0 Timeout waiting for client input (in reply to end of DATA command))
- deferred (host domain-co-nz.mail.protection.outlook.com[220.127.116.11] said: 451 4.7.0 Timeout waiting for client input (in reply to end of DATA command))
Any ideas in which to sort the issue....