How to migrate to a new mail server?

September 20, 2006 9:06 AM

Migrating email when changing web hosts. How to make it less painful?

I currently have two domains hosted in a Unix environment. I am moving both domains to a new host, using a Windows environment. I currently have about twenty email users, several of whom primarily use the web email client and who leave messages on the server.

During the transition, I can change the mx settings on the current mail server so any new arriving mail gets sent to the new host's mail server, that's not a problem. My question is, is there any way for me to actually move the contents of the various mailboxes from the current mail server to the new one, or will I need to require my users to pull down all of their messages locally or else lose them?

posted by Lokheed to computers & internet (6 comments total)

1. Stop the current mail server.
2. Update it so all new mail is automatically forwarded to the new server.
3. tar mail directory. Move file to new host.
4. untar mail directory.
5. Ensure new server is working properly.
6. Update MX settings.
7. Restart the old server.

Doing this at night, or when ever the least amount of traffic is moving over the mail server, would be the ideal time.
posted by chrisroberts at 9:50 AM on September 20, 2006

chrisroberts: Did you miss the part where he said he's moving to a Windows environment? There's a very good chance that the tar dance will fail miserably.

Lokheed: What is the new environment running for a mail server? That's a key thing right there. Perhaps it has some sort of import function. Maybe it can read an mbox. is the old host on mbox or maildir?

If both hosts support IMAP, it might be easier for you to write up a document for the users telling them how to create a new IMAP account. Then they can move messages from the old host to the new one. That's one way of doing it. The other way involves you doing pretty much the same thing, but you do the work for them.

I think the most important thing we need to know is software versions and what format you're storing the mail in.
posted by drstein at 11:06 AM on September 20, 2006

drstein: Yes, I most certainly did miss the "moving to Windows environment." Anyway, if both servers are using IMAP, you might look into this tool.
posted by chrisroberts at 11:43 AM on September 20, 2006

The best method really does depend on what server software/mailbox format is used on each side. But from the lack of detail, I'm guessing you don't really know, and the host is providing the mail service.

If both hosts provide IMAP support, using imapsync would probably yield the best results. You need to either reset each user's password so you can access their mailbox, or have an administrative account that has the proper IMAP permissions.

If users are POPing their mail and not leaving it on the server, you really can't do anything for them. Their mail only exists on their own machines. If they are using POP and leaving their messages on the server, you could use fetchmail to POP it from the old server and mail it to the new server. Again, you have to have the password for each user, but you're probably going to have to reset them anyway on the new host. And I think you're going to lose things like the read status and received date (I'm assuming this; there might be methods to preserve this data. It certainly still exists in the mail headers).
posted by team lowkey at 2:00 PM on September 20, 2006 [1 favorite]

I just double-checked, and the hosts on both ends support IMAP. I'll be able to use imapsync to move things over, which will make my users very, very happy. For those people who only POP, it really doesn't matter either way. They will have to change the settings in their mail client, but other than that it should be pretty seamless.

Thanks so much!
posted by Lokheed at 3:11 PM on September 20, 2006

Great! I'll just add that you'll want to use --subscribe (if they have subfolders) and --syncinternaldates (to keep the dates and therefore the webmail sorting the same) switches. Good luck.
posted by team lowkey at 3:26 PM on September 20, 2006