Yesterday, a strange problem happen with sendmail, i've not been able to understand why.

Sendmail was running fine since many week and for a unknown reason without modification this was happen :

Jul 2 18:28:13 bidon sendmail[10976]: m62GSCED010976: <mchironnaud@bidon.fr>... User unknown

When i watching maillog nothing special happen, it worked fine one minute before and after i've had user unknown for everyone.

No configuration file was modified , all was checked and i've not find any reason

sendmail configuration, Virtusertable, rights, mbox, users, shadow, etc .... wasn't modified since a while and after the probleme was the same than before.

I've didn't find a way to get it work a new time, i've destroyed the domain and mailbox with virtualmin and created new one, same problem again

So for my customer i've finded the solution by the way to use postfix and make a restore.

With postfix all running fine, with sendmail we loop on user unknown without reason because configuration was checked and is fine.

If you have idea , i take.