I am having some issues with the sendmail config on one of my servers.
I have several domains defined in the sedmail.cw file. When the server
was originally configured, it was never intended to host more than one
domain. So all the aliases for the initial domain (say a.com) were
created in the aliases file. Once new domains started to be added to
the servers, I started using the virtualusers file for creating
aliases (say foo@b.com). The problem is when users from a.com domain
as sending e-mails to users at b.com, the from address is being
rewritten to @a.com address. For example if foob@b.com is sending an
e-mail to fooa@a.com, the from address is being changed to
foodb@a.com. This does not happen when the e-mail is being sent to
other domains not hosted on this server. On a side note, the
MASQUERADE_AS option in the sendmail.mc is set to "a.com".

Is there a special rewriting rule I need to add to the sendmail config
file? Thank you.

After you change your virtualusertable you need to rehash sendmail. 
I'm going post a script (which you may need to change the path to the
virtualusertable) and it will fix you up.  Also, you need to ensure
that your domains are listed in your local-host-names file.  If you
don't have one, you should create one in your mail dir (example:
/etc/mail).


Just copy the script and put it into a shell file (.sh) on your
server.  Chmod it and your all done.

Paste from here ...


#!/bin/sh

if [ "$1" = "-h" -o "$1" = "-h" ]; then
	echo "Usage: $0 [-v | -h]"
	echo "  -v: show actual output"
	echo "  -h: show this screen"
	exit
fi

if [ "$1" = "-v" ]; then
	newaliases
	makemap -v hash /etc/mail/virtusertable < /etc/mail/virtusertable
else
	echo -n "Updating aliases.. "
	newaliases 1>/dev/null 2>&1
	echo "done"
	echo -n "Updating virtual user table.. "
	makemap -v hash /etc/mail/virtusertable < /etc/mail/virtusertable 1>/dev/null 2>&1
	echo "done"
fi
echo -n "Sending HUP to sendmail.. "
killall -HUP sendmail
echo "done; update complete."

If you have problems putting up that script, or have questions about
it, you can email me: exileonmain@gmail.com