Unknown user bug

[jm jm]

Hi,

I have the following problem with IMP, and I heard that some other people 
have the same one :

When a user "foo" connected with IMP send a mail to another local user "bar", 
and if "bar" doesn't exist, the sender never receive the bounced "user 
unknown" mail and then can't know that his mail hasn't be delivered.

The bounced mail is received by the user wwwrun, which is my apache deamon 
user on the server.

In the sendmail logs, the mail appears as if it was send by wwwrun instead of 
the real sender "foo".

The same test done from a local mailer on the server (pine in that case) show 
that the bounced mail comes back normaly too "foo" with the "Unknown user" 
error message. 

If the mail is send from IMP to an existing user, all is perfect and the 
receiver view a mail coming from "foo".

Is it a known bug in IMP and is there a way to correct it?

Thanks,
Jean-Michel.