Redundant mail servers
I plan to use 2 mail servers, each at different network centers on different lines. mail1 will handle normal everyday email, and should mail1 go down, mail2 starts accepting all email until mail1 comes back.
That's easily doable with MX records. The problem is, how do I get mail2's email to mail1 when mail1 resurfaces?
Or, how can I set it so that when people check their email, it checks mail1 and mail2 (I don't think that will work, but it's an idea).
Another problem, when mail1 is down and mail2 is accepting email, how do I get customers to check mail2 for their new email while mail1 is down without them making any configuration changes?
What I'm aiming for is a transparent redundant mail system. The customers won't know if the email is coming from mail1 or mail2, all they know is it's coming from "mail.whatever.com." In the background, mail1 always provides the email, and mail2 kicks in when mail1 goes down. I don't really care about the data on mail1 so long as the new email gets sent to mail2 and customers get the new email off of mail2. When mail1 resurfaces, mail2 sends its unPOP'd captured email over to mail1 and customers automagically get their mail from mail1 again and mail2 stands by again, empty and waiting.
I would rather the solution be as bandwidth friendly as possible, aka not mirroring servers continuously. Mirroring periodically might be a solution. I would also like to stay away from NFS, but if that's the only way, that's the old way...
I know this problem has been solved before but I cannot find it on the internet anywhere. All the forums I've tried had threads with the problem, but no posted solutions.
Don't be shy, even if you don't know how to fully do it, if we can get pieces together maybe we can work the whole system out.
I appreciate your help!
