[Mailman-Users] To: is being rewritten by some mail agents

[Brad Knowles]

At 10:21 AM -0700 2006-07-13, Scott Chapman wrote:

>  How does one implement the real solution when the DNS records that are
>  being virtual hosted are from different registrars? Since I only have one
>  IP address, the reverse DNS would have to be handled by the outfit I'm
>  hosting from, right?

Whoever assigned you that IP address should have full control over 
the reverse DNS for that IP address, and they should be the ones to 
make sure that the reverse DNS matches whatever forward hostnames you 
want to point there.

If not, then you're using the wrong hosting provider, and you need to 
find someone else.

>  I didn't know you could even have more than one name come up in a reverse
>  DNS lookup.  I thought it was always supposed to be the canonical name
>  only (if I'm using that term correctly).

There can be more than one "canonical name".  Any name that resolves 
directly to an IP address is considered to be in canonical form.  A 
"CNAME" record is actually an alias that should point at a canonical 
name, so while they chose a very bad name to give it, it actually 
makes a kind of twisted sense if you think about it.

>  I also wonder why the RFC's require address canonicalization in email
>  like that.  That seems a holdover from a bygone era.

It's an old requirement.  It's been around about as long as Internet 
e-mail has existed.  Many, many, many applications have been written 
to this standard, and continue to be in operation.

Would you have everyone on the Internet throw out all their server 
software, just because you don't want to be bothered to adhere to the 
same standard everyone else does?  Would you want to have to throw 
out all your server software, just because someone else decides that 
there is some old rule that they don't want to be bothered to have to 
conform to?

>  The reason I have all the CNAME's is so that I can move to a different
>  IP address and have to change the DNS record in only one place.

Yup.  That's the reason for it.  Problem is, it doesn't play well 
with e-mail or in nameserver records.

Internet e-mail existed long before the DNS did, so they have the 
right to bring with them old requirements (to which old software has 
been written and is still in operation), and nameserver records were 
invented as part of the DNS, so they also have the right to have 
their own rules.

>                                                                   I don't
>  mind getting rid of the CNAME's but getting the reverse DNS all
>  configured correctly will be interesting.

Yup.  That's a problem that everyone has if they want to host 
multiple domains on the same machine.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

  Founding Individual Sponsor of LOPSA.  See <http://www.lopsa.org/>.