stripping off domain part of address

I'm seeing something funny with our email configuration.

We are using procmail as our local mailer on our BSDI Unix server. It seems
that the domain part of the email addresses in the To: and cc: fields are
being srtipped off. Therefore we can not reply all.

Can anyone offer any suggestions on this problem.

Thanks
Steven Morris
smorris(_at_)feist(_dot_)com