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Best practice to move mail servers

I have to move email hosting from one server to another and are looking for the best practice for this procedure, in terms of continuity of email delivery with the least amount of changes at the email client level.

Currently, we are hosted on one server that all of the MX records are pointing to.  Email clients are checking this mail server for new email and are leaving mail on the server for up to 10 days before deleting it.  Most employees are also using iPhones and iPads to check email.  All email clients are using POP and SMTP.

I know I can configure the new mail server, confirm it works, then switch the MX records, BUT the time it takes for the changes to get picked up all over the Internet means that some mail will continue to be delivered to the current server while some gets sent to the new server.  The same applies to the email clients.  Some clients will pickup the DNS change and start checking the new mail server (this assuming that I use the same mail server name and just update the IP), while other email clients will continue to check the old mail server for longer.

So what is the best practice to move to a new mail server, while allowing the email clients to get every last new email from the old mail server, then switch over without issue to checking the new mail server, all the while without having to visit and touch every client to setup a new mail account to check both servers during the transition?
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Top Expert 2011
1.  Use a backup MX service such as http://www.mxsave.com/services-backup-mx.html
2.  Add the backup MX with a priority higher than your primary MX
3.  Change TTL of all MX records to 300
4.  Wait for a duration equal to the original TTL value of your primary MX
5.  Turn off your primary mail server so all mails go to the backup MX
6.  Add your new primary MX record with lowest priority
7.  Remove old primary MX record
8.  Wait for backup MX to resend or flush backup queue manually

As long as the backup MX uses DNS to lookup where it should forward mail for a domain, or if you manually configure the backup MX to route to your new primary MX, then you should be fine.

Top Expert 2011

Oh, and you should change your MX TTL's back to at least 3600 once the migration is complete.


I review that service and get back with any questions.
Aaron TomoskyDirector, SD-WAN Solutions

I second the approach and I'll add another service for you to check out. Dyn.com backup mx
Last I VHS led it was $40/yr. I recommend all my fliers with their own mail server have it or something like it.

Depending of what email server software you are using, you could set up pop-fetching on the new server most modern mail server software have the functionality.

You set up your accounts on the new server.
Use the pop-fetcher to get mail from the old server to the new with a 5 minute interval.
Move all clients to the new server.
Change your MX-record.
And finally disable the old server and the pop-fetcher.

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