I am trying to come up with a solution for office email, and I have been having a hard time making it work. Basically, 75% of our email is intra-office so it is a complete waste of bandwidth and time to send it out to our web server and then retrieve it again on another computer ten feet away. Large attachments are causing a lot of bandwidth problems, and if these emails could stay on our LAN, it would fix a lot of problems. I have 2 servers, we'll call them Web and Inhouse. I would like the local computers to send and receive email through the Inhouse server. I would like any email from outside networks to go through the Web server. The web server then needs to forward email it receives to the Inhouse server, which it can be retrieved by a user. The easiest way seemed to be a domain level forward from the Web server to the Inhouse server, but I can't forward a domain to the same domain. I could forward it to a different domain on the Inhouse server, and then forward it again to the main domain on the Inhouse server, but this seems excessively complicated. Anyway, looking for suggestions on how to accomplish this. Both servers a Linux based running cpanel. I would prefer to do this through cpanel, or DNS and not through a complicated Exim rule or something similar.
on the web server, edit /etc/mail/sendmail.cf and set the RELAY host to the IP address of the in-house mail server. Be sure to add the IP/hostname of the web server in /etc/mail/access on the inhouse email server so it will accept the emails. James
Why do you want the emails to go to the web server if they'll eventually end up at the office server? You could just set the office server as the primary MX. If you really want the mails to be stored separately (i.e. global mail on the web server, local mail on the office server), set your internal DNS to deliver emails to the local server. (you'll need to setup your domain on the internal DNS and set an MX record pointing to the local server's IP).
The main reason we want to do this is because the web server is far better setup to filter the external load of spam and crap that we get. We're averaging something like 90,000 inbound spam emails a day, and a few thousand more with viruses. For the sake of bandwidth, I want to prevent all the crap from hitting our internal network. My original thought was to use just the internal server and use seperate internal DNS for computers on the LAN. But, the spam and junk emails still come through to our network. This way solves about half the problem because at least internal emails never leave the LAN. The relay in conjunction with internal DNS sounds perfect, but I need to determine whether our filtering is going to filter and relay. I think that it may not filter at all if a domain is set to relay the emails. Anyway thanks for the suggestions. One of or a combination of these should work after some testing and configuring.