[cobalt-users] Sendmail crash every week - Qube 2

["Alain LAROCHE" <laroche@xxxxxxxxxxxxxxx>]

Hi list,

I have a serious problem.
I have a Qube2 located in a DMZ 
I have all the security patches installed on my Qube:
Cobalt OS Release 4.0 and
Qube2-All-Security Release 4.0.1 XXXX

Sendmail is refusing the pop login to my 40 users.
This is happenning  almost every week after a cron monitor.
The only way to solve this problem is to reboot the Qube.

I have plenty of "sendmail[788]: NOQUEUE: Null connection from myhostname" located in my maillog.

On a previous post someone told me that this message was comming from a "flacky" network,
so
I have changed my cross cable to a new one, from the Qube to the Firewall,
I have changed the firewall by a spare
I have check that no particular problem happends on my eth, such as looses packets, with stats,
I have increased the number of connection per minute to 255 on the qpopper config

and the crash still occurs

I have the feeling that the problem is comming from the last OS update, especially the qpooper update,

Could someone has any suggestion please ?
How can I turn back to a OS 3.0 level ?

Thank you for your help
Alain LAROCHE