postfix: strange behaviour

[Boris Glawe]

Hi,

I'am using postfix as smtp server on my FC3 machine.

Received mails are forwarded locally to the cyrus-imapd.

Yesterday I decided to update my system (yum -y update). Yum downloaded 
hundreds of MB of rpm packages and stored it somewhere in /var/spool. 
The /var partition was not big enough, so I decided to copy the content 
to another partition and replace the /var/spool directory by a link.

As a result postfix did not accept any connections any more, though the 
start scripts did not report any errors. The logfile /var/log/maillog 
told me something about "pid/inet could not be locked explicitly: no 
such file or directory" and later it said something about "postfix/smtpd 
exited with status 1" (it's not the exact message, it's only what I 
remember - also the filename(s) might be a little different). The file  
/var/spool/postfix/pid/inet existed though and was readable!!

After a long time of trying to find a reason for this behaviour, I 
decided to move the spool directory back to /var, backup my 
/var/spool/postfix directory, remove the /var/spool/postfix directory, 
to uninstall postfix (yum -y remove postfix), removing /etc/postfix, 
installing postfix again and restoring the config file in /etc/postfix.
I also executed "fixfiles relabel", though there were absolutely no avc 
denied messages in /var/log/messages.

With the next start of postfix /var/spool/postfix and it's 
subdirectories were created again automatically. I also restarted 
saslauthd and cyrus-imapd dozens of times.
BUT: the same error again.

And what was the solution? Restarting the whole system! After having 
rebooted, postfix worked fine!!

How's that possible? Postfix did not leave any files in /tmp or in 
/var/tmp. During the system shutdown, the same start/stop scripts in 
/etc/init.d are used, which I use for shutting down and starting the 
three services. Postfix had been uninstalled completely in the meantime. 
There were no processes left that were connected in any way with mail 
transfer after having stopped saslauthd, cyrus-imapd and postfix. What's 
a system restart doing, that makes postfix forget any settings, that 
were responsible for this behaviour?

Thanks for any hint!

Greets Boris