Orin, > This week the server farm where we have our iMail server suffered > some significant problems...In the muck up we had our server out > intermittently...
Luis has outlined the most common kind of redundancy, which is offered by the DNS itself in the form of multiple MX records; he mentions that having two MXs at the same colo wouldn't solve colo-wide issues (such as those you had). Rick is strong on the WAN side and has given you an idea of the complications of setting up multiple colos--if you're going to do it right, you have to know who's peering with whom and where, who's on the brink of bankruptcy, etc. Now would probably be a good time to put up a store-and-forward secondary MX, just to get used to the concept. Once it has a record in DNS, you can move it to another colo as necessary just by changing the published IP. For this secondary, you could use MS SMTP or get another license for IMail. Your secondary MX normally just holds on to messages until your primary comes back up (usually with a short queue retry period and a longer queue lifetime to reduce the number of bounces back to the originator), so no messages are ever delivered locally to that box. MS SMTP, or any MTA, will thus suffice. If you use IMail, you have the additional option of, in a pinch, turning your secondary into a mailbox server and letting your users access their mail via the web. You'd do this by keeping a dummy domain (say, backup.example.com) on the backup server and frequently synchronizing it with your main mailbox server via Registry backup-and-restore. In a longer-term emergency, you could add example.com as a host alias under backup.example.com, causing mail to be temporarily delivered locally to the box. Of course, this would only apply to messages sent after the outage began. (A more extreme version of this would be to set up both boxes as mailbox servers and set every client MUA to pull mail from both. This can cause major setup and management headaches and is not advised; one immediate casualty is webmail, which can go out of sync even if there's just a blip of downtime on the primary.) Additional redundancy options involve real-time mirroring of your userbase across geographical locations--things your budget probably doesn't allow. Why don't you wait for a few days to see if things cool off? There's often a panic period in which The Boss wants this to "never happen again"--then reality sets back in. :) -Sandy To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
