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-   -   MX DNS Records (http://www.howtoforge.com/forums/showthread.php?t=61340)

mrrow 8th April 2013 16:52

MX DNS Records
 
I would like to know what to put for the MX records of client sites I host.
Environment:
server.com - 123.123.123.123 - This is the address and IP of the physical hardware. It runs the mail server, mail.server.com
client.com - This is the domain name of the client website.

I have a few choices as I see it.
1. Just set the MX record to mail.server.com for every client.
2. Set the MX record to mail.client.com and have an A record pointing mail.client.com -> 123.123.123.123
3. Set the MX record to mail.client.com and have an CNAME record pointing mail.client.com -> mail.server.com

I'm trying to figure out what the best thing to do is from:
1. A maintenance point of view (likely to move servers in the future)
2. Receiving servers point of view (are any of the options less likely to get email from user@client.com bounced / help with reverse DNS lookups)

Thanks in advance.

ISPConfig: 2.2.35
Ubunutu: 2.6.39.4-x1-64

Parsec 9th April 2013 02:45

Quote:

Originally Posted by mrrow (Post 295516)
server.com - 123.123.123.123 - This is the address and IP of the physical hardware. It runs the mail server, mail.server.com
client.com - This is the domain name of the client website.

I have a few choices as I see it.
1. Just set the MX record to mail.server.com for every client.
2. Set the MX record to mail.client.com and have an A record pointing mail.client.com -> 123.123.123.123
3. Set the MX record to mail.client.com and have an CNAME record pointing mail.client.com -> mail.server.com

Well, you can do it whichever way you like although option 3 is most probably better then 2. However Option 1 is actually the best, especially if your clients start using ssl methods of transport. Assuming mail.server.com has a valid ssl certificate, then the clients will connect without issue, however if you use their domain name and the server responds with it's ssl cert (mail.server.com) they will always get an error popping up in their client.

Quote:

Originally Posted by mrrow (Post 295516)
I'm trying to figure out what the best thing to do is from:
1. A maintenance point of view (likely to move servers in the future)
2. Receiving servers point of view (are any of the options less likely to get email from user@client.com bounced / help with reverse DNS lookups)

1. Actually another way is to have a cname for mail.server.com and this server has a wildcard ssl for *.server.com, then you merely create a cname for the server eg: smtp1.server.com cname mail.server.com. In this way if you ever change or get a new server and it's called mail3.server.com you can use the same ssl and just change the cname (smtp1.server.com cname mail3.server.com) - thus clients just keep their existing setup in their email clients eg: smtp1.server.com

2. Doesn't matter, the other end will always see the mail as coming from mail.server.com so as long as that has the corect rDNS you should be fine.

mrrow 9th April 2013 15:41

Thanks for the quick reply.

I'd totally forgotten about the SSL aspect of this, I think I'll have to go with option 1. (Just set the MX record to mail.server.com for every client.) because I don't want folks ringing me up re certificate errors.

I don't really want to fork out for a wildcard certificate so I think when I move server I'll set up mail1.server.com, buy an ssl for mail1, shift the accounts, and then add mail.server.com CNAME mail1.server.com.

As part of the move I was looking to expand to a couple of servers, and move sites and email clients between servers as necessary to balance the load. I was hoping that by using option 3, that I could change the CNAME records and make the move transparent to the end customer. E.g.
Before: Client1's email boxes on mail1.server.com and mail.client1.com CNAME mail1.server.com
After: Move the client1's email boxes to mail2.server.com and do mail.client1.com CNAME mail2.server.com

Is there anyway to achieve this without getting certificate errors? Maybe a way to redirect (like a web 301) mail.client1.com to mail2.server.com. Basically, looking for a way to move some email boxes without having to trouble the customer.

Thanks for your help.

Parsec 9th April 2013 23:24

I guess it depends on what you offer your existing clients now. if they are connecting to mail.client1.com, does it have a correct ssl certificate? If you don't have any existing clients using an ssl connection method then you might get away with the cnames.

I know moving clients to new servers is always a problem unless you are a big company with huge resources, there never seems to be an easy way.

Theres not much I can help you with about moving existing clients to new servers - best bet is to test it with a dummy setup and see what happens yourself, and see what you can do to get around the problems.

I do suggest however, if you are going to have multiple servers to serve your clients you look deeper into having all your servers under the one domain and using a wildcard ssl. if you hunt around you can get a wildcard for a reasonable price - compared to buying individual certs for server1, server2 etc. It's something to look into as it helps with a number of other things not just mail. Maybe check out places like godaddy and search around for coupon codes - you can often end up with a price not that much different to buying a couple of standard certs.

mrrow 9th April 2013 23:38

Thanks Parsec,
I'll have another look at wildcard certs again.


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