OS: Debian
Mail Server : PostFix
AV: ClamAV

I have a newly created SMTP mail server and so far, everything is going great. Over 300 mails are being sent a day and no major issue has come up since then.
However, the thing is that every morning I'm rotating my logs so that mail.log becomes mail.log.0 and so on.
Its working fine but this morning, mail.log after having been empty and rotated, is empty and nothing is being logged anymore in it.
The strange thing is that mail.info is but not mail.log.
Mail server is still working well, syslog shows nothing strange, mail.err either, everything is working smoothly as its always been since I started everything, but my mail.log is being kept empty.
The reason why I need that log file is that it’s being used by pflogsumm which sends me the server stats every morning.

Anyone has a clue about this issue?

Is there any info I can post in that thread that would help you guys help me with this issue ?

I did not found the cause, but at least I found a way to fix it, and even make sure it does not append again.
I've added in the server CronTab these 2 lines of code :

kill -HUP `head -1 /var/run/rsyslogd.pid`
/etc/init.d/postfix restart

Killing the rsyslog process fixes my probleme, rebooting the mail server make sure everything re-initialize correctly and doing it every day after the server maintenance keeps everything clean.