[CentOS] Postfix won't relay after update to CentOS 4.4

Fri Sep 1 05:10:35 UTC 2006
Kanwar Ranbir Sandhu <m3freak at rogers.com>

On Fri, 2006-01-09 at 11:06 +0800, Feizhou wrote:
> or grep 'postfix/smtp\[' /var/log/maillog
> and look for messages related to sasl and/or sasl_passwd.db

I'd already done that before, but I thought maybe the results warranted
another look (after a several hour break).  I'm glad you suggested the
above because I now I have the relay working again!

The smtp server my ISP tells its customers to use is
smtp.broadband.rogers.com.  When I grepped maillog, I noticed messages
from Aug 30 were going out successfully like this:

relay=smtp.broadband.rogers.com[], delay=1, status=sent
(250 ok 1156773933 qp 73034)

However, messages from Aug 31 were giving this error:

relay=smtp-rog.mail.yahoo2.akadns.net[], delay=0,
status=bounced (host smtp-rog.mail.yahoo2.akadns.net[]
said: 530 authentication required - for help go to
http://help.yahoo.com/help/us/mail/pop/pop-11.html (in reply to MAIL
FROM command))

Interesting: there's been a change at the ISP.
smtp.broadband.rogers.com is now pointing to
smtp-rog.mail.yahoo2.akadns.net.  I changed my postfix config to include
the new smtp server name, and my emails started heading out again.

I don't know enough about the process to know exactly what happened, but
it looks like Postfix attempted to auth directly to the old server.
When it was "forwarded" to the new server, the login failed.

I'm puzzled why the manual test I performed worked using the old server
name, but wouldn't with Postfix.  Anyone know the details about the auth
process to explain what happened?

Anyway, I'm just glad it's all running again.  I'm even happier that it
wasn't the postfix update that messed things up.

> the smtp daemons will run as postfix user and so sasl_passwd.db has to 
> be readable by postfix user.

Actually, postfix starts as the root user, reads everything it needs to
get going (including the sasl_passwd.db file), and then drops privileges
to the postfix user.

Thanks Chris and Feizhou for your help.  I appreciated the replies very


Kanwar Ranbir Sandhu
Linux 2.6.17-1.2142_FC4 i686 GNU/Linux 
01:09:26 up 2 days, 18:38, 2 users, load average: 0.04, 0.18, 0.37