How do I setup exim to send emails from mutiple domains?

Question

I have a centos 5 box running exim. The box hosts many domain names which send outgoing email. The problem is that the emails show that the email is coming the box's hostname (say x.com), rather than from each domain name (y.com and z.com). How can I set this up so that an email sent from y.com actually says that it's coming from y.com?

Answer 1

If you are asking about the host name in the Received: header this is correct behavior. Just add an MX record for all your domains referencing the box's hostname. Also consider adding SPF records to the domains. If your server is Internet facing, it needs a static address, and it IP address should have a PTR record returning its FQDN (Fully Qualified Domain Name).

If you are asking about what recipients see in their mail clients this is determined by the mail user-agent sending the message: If it puts the appropriate From: or Reply-to: headers in the outgoing e-mail, these should show up appropriately when the email is read.
For exim you can put entries in /etc/email-addresses to change the default domain and/or name for particular users.