Postfix: Lost connection while receiving initial greeting

[Salim Hoolash]

Dear All,

First of all, thank you in advance for your help. I had a server running Ubuntu 10.10 with postfix as MTA and mails were being sent out. I just replaced the server wih a new one running Ubuntu 12.10 and suddenly no mails are sent out.
postqueue -p output yields:
(lost connection with mail.example.com[10.XXX.XXX.49] while receiving the initial server greeting)
However when I try telnet 10.XXX.XXX.49 25, I am connected to the mail server and I can send a mail using ehlo, mail from, rcpt to etc.
Any idea what may be wrong?
Thanks.

[falko]

Are there any errors in your mail log (in the /var/log/ directory)?

[Salim Hoolash]

falko,

Thanks for the reply.

Feb  4 11:50:52 Nagios-PC postfix/qmgr[12807]: C98AA11CB000: from=<root@PACE-Alarms>, size=321, nrcpt=1 (queue active)
Feb  4 11:51:13 Nagios-PC postfix/smtp[21065]: C98AA11CB000: to=<salim.hoolash@mauritiustelecom.com>, relay=mail.mauritiustelecom.com[10.225.225.49]:25, delay=20, delays=0.14/0/20/0, dsn=4.4.2, status=deferred (lost connection with mail.mauritiustelecom.com[10.225.225.49] while receiving the initial server greeting)
Feb  4 11:57:04 Nagios-PC postfix/qmgr[12807]: C98AA11CB000: from=<root@PACE-Alarms>, size=321, nrcpt=1 (queue active)
Feb  4 11:57:25 Nagios-PC postfix/smtp[12358]: C98AA11CB000: to=<salim.hoolash@mauritiustelecom.com>, relay=mail.mauritiustelecom.com[10.225.225.49]:25, delay=392, delays=371/0.01/21/0, dsn=4.4.2, status=deferred (lost connection with mail.mauritiustelecom.com[10.225.225.49] while receiving the initial server greeting)
Feb  4 12:07:04 Nagios-PC postfix/qmgr[12807]: C98AA11CB000: from=<root@PACE-Alarms>, size=321, nrcpt=1 (queue active)
Feb  4 12:07:25 Nagios-PC postfix/smtp[16287]: C98AA11CB000: to=<salim.hoolash@mauritiustelecom.com>, relay=mail.mauritiustelecom.com[10.225.225.49]:25, delay=992, delays=972/0.01/20/0, dsn=4.4.2, status=deferred (lost connection with mail.mauritiustelecom.com[10.225.225.49] while receiving the initial server greeting)

Salim.

[falko]

Please check if your server is blacklisted: http://mxtoolbox.com/blacklists.aspx

[Salim Hoolash]

falko,

You put me on the right track. Since our mail server is on a private address, I could not verify whether my IP address was blacklisted with the site you mentioned. So, after investigation with my ISP provider, I found out that they have 2 mail relay servers one on address 10.XXX.XXX.49 and the other on 10.XXX.XXX.50. I figured out that I could not authenticate on the '50' one but it was OK on the '49' one. So, instead of having 'relayhost = Blank' in /etc/main.cf, I added relayhost = 10.XXX.XXX.49 thus forcing mails from my server to relay through address '49'. Now, mails are flowing without problem.

Thanks a lot for your help.