Multiple MX Records Pointing to Multiple Servers for a Single Domain – Setup Guide

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Is it possible to have multiple MX records pointing to multiple mail servers for a single domain? Must all mail accounts be identical on each of those servers, or is it possible to have email1@mydomain.com set up only on one mail server, and email2@mydomain.com set up only on the other mail server?

The reason for this is the need to use two different email service providers but still keep everything at a common domain.

My understanding of MX record functionality tells me this scenario won't work, that each server will respond with "mailbox not found" errors for the accounts not on that particular server. Help?

Best Answer

Yes, you understand it correctly.

Sending E-Mail servers use MX records in order of preference defined within the MX records. The record with smallest precedence is used first, then the second smallest etc.

If two servers have equal precedence, the sending server picks a random server from the equal precedence server.

You can make forwarding accounts on server 1 that only forward all e-mails to server 2. This would effectively solve your problem.

Related Solutions

Help: Setup Outgoing Mail Server Only for Multiple Domains Using Postfix

Since you're running Ubuntu, you should be able to get a functional postfix setup by running

dpkg-reconfigure postfix

This should run a dialog that asks you a series of questions. One of the questions will be along the lines of "Other destinations to accept mail for", to which you should reply with an empty string (i.e. blank). You should also be certain to give a valid email address (e.g. yours) in answer to the question "Root and postmaster mail recipient", so that mail generated by the system by/for system users gets delivered somewhere.

When pointing to new DNS servers is there any chance of E-mails being lost even if the old E-mail hosting service is still up

After the new mail server is ready to accept mail for your domain via smtp and serve mail via imap and or pop or the like, then you want to change the old server to forward mail to the new server. Get all this working BEFORE you change MX records. Then it doesn't matter if mail arrives at either the old or new server, since it all ends up at the new server, eventually.

I dislike people using the term "propagation" when referring to most DNS changes, as I find that most people are being mislead to what is going on. Typically DNS changes are instantaneous, there is no need for propagation. Propagation only happens when you are changing the nameservers at the registrar, and these changes need to go out to all the root DNS servers. This is an operation that used to take many hours in the (distant by internet standards) past, but no longer takes much time. These days when people talk about propagation, they are usually incorrectly referring to DNS TTLs.

Whenever an authoritative nameserver answers a DNS question (like what are the mx records for this domain), that answer comes with a TTL, which says "here is your answer. You can assume this answer is the correct answer for X seconds". So if you have a very long TTL on your MX records, and then change them. People that looked up your MX records might cache the results for a long time, and therefore, after the change, will be sending mail to the wrong server for a long time. If you are anticipating a change in DNS records. You can drop the TTL to something small until after the change.

Best Answer

Related Solutions

Help: Setup Outgoing Mail Server Only for Multiple Domains Using Postfix

When pointing to new DNS servers is there any chance of E-mails being lost even if the old E-mail hosting service is still up

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