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I'm preparing a move from our online provider e-mail to our own cloud hosted Microsoft Exchange Server.

I'm looking at our current DNS records in the provider config panel regarding email:

  • MX [10], mail.mydomain.com
  • MX [21], mail2.mydomain.com

  • A mail 85.121.4.110

  • A mail2 85.121.4.110
  • A pop 85.121.4.110

What's interesting to me is that the secondary mailserver is the same as the primary. Could there be any use for this?

Seams to me like when the primary is down the secondary is also down right? So I have no clue why this second mx entry is in there?

So I'm wondering can I just remove that second entry? Then I'm only left with the first entry and I will point that one to the new mailserver. (for now we only have one mailserver)

Can anybody confirm the usage of the second MX record and if I can just remove it. (along with its A record)

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3 Answers

up vote 1 down vote accepted

It does seem that the secondary MX record would be invalid but without knowing the infrastructure for your current provider we can't say for sure, I would suggest using a new record for your new server and only once you've migrated over and upped the priority on the new record and everything is running through that server would I remove the old MX.

You don't have to reuse MX records you can have as many as you want called whatever you like, the most I've seen one company use is 8.

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Hi and thanks, well the only think I know is that the mailserver is smartermail. I have no clue what the infrastructure of the provider is. What I do know is that both addresses work. You raise an interesting point creating a new MX record. So would the good idea here be to create something like: webmail.mydomain.com with a higher priority so its served first? then if this works remove the others? –  Joost Verdaasdonk Jun 7 '12 at 18:25
    
Yep, that's the way I'd do it. The reason I'm a bit hesitant about just dropping the second MX is that there are load balancers that can work on domain names and instead of IPs, Zeus being the one I've played with, as such I would like to be optimistic and assume that this is what they have set up and having the secondary MX is a good thing at least until you migrate away. –  Chris Jun 7 '12 at 22:54
    
Ok sounds like à plan to me thanks again! –  Joost Verdaasdonk Jun 7 '12 at 23:30
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Many setup validation and diagnostic type tools complain if you dont have a secondary mx. While this doesnt provide any sort or backup, it does make such tools stop complaining.

Its similar to entering the same dns server twice for your domain at providers that require you to enter 2 dns servers. Ideally you should have a real backup mx, but plenty of people just use one.

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Hi thanks, ok this is somewhat logic because their are a lot of validating things that require redundancy. But we are a small company so for now we don't have this. So if as long as it doesn't hurt looks like I can leave it the way it is. –  Joost Verdaasdonk Jun 7 '12 at 18:21
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Since both mail.mydomain.com and mail2.mydomain.com have the same A record, you do not need both MX entires. But there is a chance that some mail clients ( IE people that have user@mydomain.com ) may be using mail.mydomain.com for their SMTP server, and others may be using mail2.mydomain.com ( from back when the email hosting got changed ).

You can clean up the mail2 A record if you don't mind spending the time troubleshooting any issues that arise from deleting it, but there will be no impact to the delivery of internet email to user@mydomain.com.

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Hi thanks. we know for a fact that only the mail.mydomain record is used so that part will be easy thanks –  Joost Verdaasdonk Jun 7 '12 at 18:18
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