[cobalt-users] DNS HOWTO - MX Record www.domain.com - Why?

["cbtrussell" <cbtrussell@xxxxxxxxxxx>]

Hi again,

My second DNS question of the day (*sigh*)

In both the "Sun CobaltT DNS Quick Start Guide"
http://www.cobalt.com/support/wp.dns.html and the Cobalt DNS HOW-TO (RaQ3
and RaQ4)
 http://pkg.nl.cobalt.com/howto/cobalt_dns_howto.shtml the examples set MX
records for www.domain.com as the mail server name.

I normally would want to use mail.domain.com, but the guide at
pkg.nl.cobalt.com has the following warning in Step 4 which makes me wary:

{start quote}
"Now to add the MX entry to allow the domain to receive mail. This is the
tricky part since it also has a direct relation to how you created the site
in the beginning.

www.testing.com is the name of the Virtual Site I created. Therefore, the
users of my site will be located there - the same users that will want to
receive email.

The general rule is the Mail Server (MX) record must point to the Address
(A) Record of the Virtual Site where you want to receive email."
{end quote}

SO - which is it? Why this funny mail server = www.domain.com business?

If I set up

A record for mydomain.com > x.x.x.x
A record for www.mydomain.com > x.x.x.x
MX record for mail.mydomain.com > x.x.x.x
(no PTR because it's a name based site)

Would this NOT work?

Thank you,

Brandon