Ubuntu – Postfix: connects and then disconnects immediately

postfixsmtpUbuntu

There has been another question like this logged before, https://serverfault.com/questions/86315?tab=oldest#tab-top, however it was never really resolved.

I have multiple instances of postfix running on one server, which all generally seem to send perfectly. However i am occasionally getting the following error:

Nov 5 12:35:21 cp postfix-ms00/smtpd[18550]: connect from x.domain.com[xxx.xx.xx.xxx]
Nov 5 12:35:21 cp postfix-ms00/smtpd[18550]: disconnect from x.domain.com[xxx.xx.xx.xxx]

Basically it connects and then disconnects immediately.

When i run tcpdump -s0 -X -i eth0 port 25 and host x.domain.com and the connect/disconnect error occurs nothing gets outputted.

Does anyone know how i can fix this?

is there a way i could watch the smtp command output? i.e: the "helo localhost" information when the mail is trying to be sent.

Best Answer

You could enable postfix debugging for specific hosts.

/etc/postfix/main.cf:
debug_peer_list = xxx.xx.xx.xxx