Benefits to separate IMAP and SMTP entries on same machine?

Question

Benefits to separate IMAP and SMTP entries on same machine?

I'm setting up the Mail Server within OSX Yosemite Server. As of right now, I've got a DNS entry for mail.xyz.com which handles both IMAP and SMTP parts of the equation. This seems non-standard when looking at traditional settings.

Mind you this is one Mac Mini.

Is there a benefit to setting up entries for imap.xyz.com and smtp.xyz.com for mail purposes, or can I even do that within the server mail app?

Thanks!

Robert

Mac mini, OS X Yosemite (10.10.3)

Posted on Aug 4, 2015 9:25 PM

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Answer 1

Best reply

John Lockwood

Level 6

13,679 points

Aug 5, 2015 3:49 AM in response to Robert Marshall

Mac mail servers like Apple's and Kerio Connect run all the services on the same mail server so just using mail.domain.com works fine. Hypothetically using separate host names would make it easier to split these tasks if you had a mail server that worked that way.

I would suggest you have an A Record aka. Machine Record for mail.domain.com and then create CNAME aka aliases for smtp, imap, and pop3 if desired all pointing to the A Record. You can then configure the clients to use separate names 'just in case'.

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Answer 2

Aug 5, 2015 2:01 PM in response to John Lockwood

Hmmm...maybe I'm missing something. I went ahead and set up CNAME records for imap.domain.com and smtp.domain.com, pointing them to mail.domain.com. This was done several hours ago.

However, when I change my account settings in Mail to reflect the new "servers" It says they're offline and cannot communicate with them.

---------------------------------

ALERT

There may be a problem with the mail server or

network. Verify the settings for account

"robertjm@domain.com" or try again.

The server returned the error: Connections to host

imap.domain.com on the default ports failed.

--------------------------------

All I did was change mail. to either IMAP. or SMTP., depending on whichever one it was supposed to be. Is there something I need to change within OSX Yosemite Server's Mail part as well?

Thanks!

Robert

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Answer 3

Aug 5, 2015 3:45 PM in response to Robert Marshall

Depending on your setup there maybe different DNS servers responsible for your domain internally i.e. on your LAN, and externally i.e. as far as the Internet is concerned. These changes would need doing on both if so. Several hours would normally be long enough for such changes to propagate.

To do some tests try the following using Terminal on a client Mac and the mail server.

nslookup imap.domain.com

nslookup mail.domain.com

ping imap.domain.com

ping mail.domain.com

For imap.domain.om you should get a result looking something like this

Non-authoritative answer:

imap.domain.com canonical name = mail.domain.com.

Name: mail.domain.com

Address: x.x.x.x

For mail.domain.com it should look something like this

Non-authoritative answer:

Name: mail.domain.com

Address: x.x.x.x

The number should be the same for both since imap.domain.com ultimately should resolve to the same address as mail.domain.com and equally ping for both should work.

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Answer 4

Aug 5, 2015 7:27 PM in response to John Lockwood

Well, I've obviously got something wrong because here's what I get when I do those look ups:

-------------------------------------------------------------------------------- ----------

Last login: Wed Aug 5 13:50:07 on console

remote_client:~ robertjm$ nslookup mail.domain.com

Server: 127.0.0.1

Address: 127.0.0.1#53

Non-authoritative answer:

Name: mail.domain.com

Address: 96.xx.xxx.xx (this is the correct IP for my public gateway)

meerkat:~ robertjm$ nslookup imap.domain.com

Server: 127.0.0.1

Address: 127.0.0.1#53

** server can't find imap.domain.com: NXDOMAIN

---------------------------

Last login: Wed Aug 5 13:50:07 on console

mail_server: ~ robertjm$ nslookup mail.domain.com

Server: 127.0.0.1

Address: 127.0.0.1#53

Non-authoritative answer:

Name: mail.domain.com

Address: 192.xxx.x.xx (this is the correct IP for the server on the LAN)

meerkat:~ robertjm$ nslookup imap.domain.com

Server: 127.0.0.1

Address: 127.0.0.1#53

** server can't find imap.domain.com: NXDOMAIN

--------------------------------------------------------------------------------

Here are my DNS settings at our service registrar:

Zone File

Last updated 8/5/2015 9:30:19 AM MST

9 records in this zone

A (Host)

2 Records (0 Selected)

Host	Points To	TTL	Actions
	@	184.xxxx.xxx.xx	600 seconds
	mail	96.xx.xxx.xx	600 seconds

CName (Alias)

3 Records (0 Selected)

Points To	TTL	Actions
imap	mail	600 seconds
smtp	mail	600 seconds
www	@	600 seconds

MX (Mail Exchanger)

1 Records (0 Selected)

Priority	Host	Points To	TTL	Actions
	1	@	mail.domain.com	600 seconds

-------------------------------------------------------------------------------- ---

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Answer 5

Aug 5, 2015 7:36 PM in response to Robert Marshall

OK, so I see where I may have went wrong. I looked at the www @ as an example and only put in imap and mail, rather than imap and mail.domain.com.

I've made that change and will check it again later this evening.

Hopefully, that's the ticket. If you've got other suggestions don't hesitate to chime in. :-)

Robert

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Answer 6

Aug 5, 2015 11:59 PM in response to Robert Marshall

And to put this post to bed with one final reply, lest it help someone down the future, I hadn't added the Alias record in my OSX Server's DNS records. Once I did that the mail started flowing in.

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Answer 7

Aug 6, 2015 5:49 PM in response to John Lockwood

The mail server needs to have an A record for whatever is associated with it — using CNAME entries will get your outbound mail filtered by other hosts (and there is nothing you can do about that, other than fix your DNS), as mismatched forward and reverse domains are not distinguishable from a spam engine.

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