Add logging info for untrusted sender

[Loïc Elineau]

>
> Should be possible by switching to "Reject forged from header" in the
> Kolab web admin "Service" tab.
>
it seems it's working without I lost mail from mailing lists. There must be 
anything wrong in the assertion:
"Always reject the message. Note that enabling this setting will make the 
server reject any mail with non-matching sender and From header if the sender 
is an account on this server. This is known to cause trouble for example with 
mailinglists. "

I'll wait a few days to validate that I don't receive any more spams from 
"UNSTRUSTED me" :D

Cheers

-- 
Loïc Elineau
http://www.benefacere.fr/