DNS and MX

[ctclibby]

Hi All

I have asked a question in a moderated list (
MIMEDefang at lists.roaringpenguin.com ) and have quite the discussion
going on.  So I now turn to you for wisdom and answers.  I have added
more information below.  Here is my question as posted:
---
Hi all

Please tell me that I am NOT weird?

Receintly I updated DNS for a few domains.  My registrar gives the
option of assigning an IP addy for domain.tld without having an alias:
mail.domain.tld  Ok, says I, lets give it a go.  Bam!  Slam, Spam
started invading my privacy.  This leads me to believe either:
   1. Mail ( spam ) in this case is being sent to domain names without
doing MX lookups.
   2. I screwed something up.

So I went in and unassigned that IP from domain.tld and that Spam
stopped.

Will look into this further to make sure that I have the domain setup
proper.

todh
---

Enom is the Registrar and I have multiple domains behind a firewall (
apache and sendmail ) of which the firewall forwards to an internal
machine.  Everything works as it is supposed to: www gets web,
smtp,pop3 and imap gets sendmail/dovecot.

I have always assumed that a domain.tld is a container for hosts; i.e.
mail.domain.tld, www.domain.tld, router.domain.tld.  Looks like some of
the folks believe that having an A record should be done so that
surfers that don't know don't have to put in the www part to get to
some.domain.tld.  Ya, Ya, thank the marketing bigbrass for that one.

So here is the big question:  Should domain.tld have an Address record
associtated with it?  What is kosher?

Thanks in advance!

todh