How to "re-write" incoming addresses to avoid bouncing..?

[John Dempsey]

Hi, again, thought I would ask each question in a separate message.

I have moved from a postfix mail system to Kolab2, and want to know
how I can redirect or re-write email addresses like 
"username at mailservername.domainname.com"
to "username at domain.com".  Postfix, at least the way I had it configured 
was more forgiving in this regard
and would accept the messages. Kolab rejects them, if they arrive from 
an external source. Sending from
and internal address to  username at mailservername.domainname.com caused 
no bounce, it just went into lala
land. I found that if I put username at mailservername.domainname.com into 
the user's alias list,
that the internal sending would work, but external still acts the same way.
I have users who are concerned that some mailing lists and users may 
have their address as username at mailservername.domainname.com, instead of 
username at domain.com, and that they mail be missing
messages.

Any ideas?

Thanks
JD