[CentOS] redirecting some addresses with sendmail

Sun Apr 9 20:13:54 UTC 2006
Tony <pthagonal at gmail.com>

I have a fully working cyrus+sendmail mail server hosting all users
for foo.com. Company foo has been acquired by company bar and it has
been decided that bar.com is the new domain of choice. The
administrator of bar.com has added a pile of redirects to send various
user at bar.com addresses so they come up to my server at foo.com. My
users have changed their From: addresses to user at bar.com and we have a
basic working system.

However, if one user in former company foo mails another user in the
same office their mail now goes offsite to bar.com's mail server and
is then redirected back in again, which works but is bad for

Ideally I'd like to teach sendmail that a subset of bar.com users are
now local. However if I try this in the /etc/aliases file, I get the
warning "cannot alias non-local names".

Has anyone got any better ideas how to do this- or a better suggestion
as to where I should ask this question again?