Re: [cobalt-users] mail problem

[Jeff Lasman <jblists@xxxxxxxxxxxxx>]

Bruce Timberlake wrote:

> > We've also found that (presuming your hostname for the domain is
> > "www") you should have a CNAME record pointing mail for
> > www.simpel-internet.com to simpel-internet.com as well.
> 
> CNAME's can cause unpredictable results, esp with email on the Cobalts
> (due to the way the 'internal' rewriting tries to happen

That was a simple brain fart <frown>.  What I meant to write, what I
should have written, is:

We've also found that (presuming your hostname for the domain is "www")
you should have an MX record pointing mail for www.simpel-internet.com
to simpel-internet.com as well.

> : mail for
> user@xxxxxxxxxx gets rewritten to user@xxxxxxxxxxxxxxxx  If
> host.domain.com is CNAMEd to domain.com, a vicious loop gets set up
> and you get the dreaded 'recursion error').  The official
> recommendation has always been to use A records instead of CNAME.

Definitely.

> In this case, would you have 2 MX records? One for
> www.simpel-internet.com pointing to simpel-internet.com, and one for
> simpel-internet.com also pointing to simpel-internet.com?

Just as definetely.  Because after user@xxxxxxxxxx gets rewritten to
user@xxxxxxxxxxxxxxx a lookup is done for the mailserver serving
host.domain.com.  Which should be satisfied by an MX record.  As we all
know, if there's no MX record, the resolver will do another lookup for
an A record, but this results in extra lookups.

> My personal setup has always been to add one more A record for
> mail.domain.com to my A record list, so I have
> 
> domain.com -> ip.ad.re.ss
> host.domain.com -> ip.ad.re.ss
> mail.domain.com -> ip.ad.re.ss
> 
> Then set up MX records for domain.com and host.domain.com to point to
> mail.domain.com.

Almost exactly; see below.

> Added advantage is that if you need to separate mail services onto a
> separate server for some reason, you just modify the mail.domain.com
> A record, and you're done.

We separate pop, smtp, and mail, so they can be directed to their own
machines as well, if/as a domain grows.

I don't believe that's necessary these days; most domains don't grow;
they simply serve static websites.  But the preparation doesn't cost us
much in the way of time; it's fully automated.

> Might be wrong, though, and I might just have been lucky all these
> years... :)

No, you're doing it right <smile>.

Jeff
-- 
Jeff Lasman, nobaloney.net, P. O. Box 52672, Riverside, CA  92517 US
Internet & Unix/Linux/Sun/Cobalt Consulting +1 909 778-9980
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