In similar circumstances, I had the same problem with IMail and
SimpleDNS Plus; of the two, I narrowed it down to just IMail being
broken, i.e. that IMail would try to deliver to secondary MX records of
it's own accord.

I would see long delivery times, for example to HotMail & MSN to name
names.

My answer for the few domains that a) had a malfunctioning MX (primary
too!) b) which suffered long delivery times (or no delivery) that I
would create a dummy DNS zone in SimpleDNS Plus and hardcode the records
that worked.

You would think that this would create more work for me, as when the
destination changes their mail configuration, my hardcoded records would
be responsible for a new mail failure.  Well, that'd be true, but in
practice these broken domains seldom made changes, so in 2 years this
rarely came up.

If you have a lite version of Simple DNS Plus, you'll probably want to
create some kind of counterweight for them so that you are more likely
to accept mail from them.  This is because the number of zones you
create is limited by your lite version, and creating both the forward
and reverse lookup zone would count as 2 zones.

Andrew 8)

p.s. Since moving to using IIS for my outbound mail handling, I haven't
needed to use any of this sort of "cheat".

p.p.s. At least one outsourced\disaster-recovery mail provider suggests
that you configure your DNS to make them the highest cost MX record, and
they return a 421 response until you tell them to "turn on" mail
handling and webmail for your domain.

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Erik
Sent: Saturday, February 19, 2005 10:17 AM
To: [email protected]
Subject: RE: [Declude.JunkMail] OT: Imail / DNS / and 2nd MX records


Thanks.... So do would need to make a change to our DNS cache - to
expire sooner?  It is just strange that it is only happening on this
domain (as far as we are aware).  And the only reason we are aware of it
is that domain has a second MX that does not accept email; so it's being
returned to sender.

Erik


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Sanford
Whiteman
Sent: Saturday, February 19, 2005 7:04 PM
To: Erik
Subject: Re: [Declude.JunkMail] OT: Imail / DNS / and 2nd MX records


> Sometimes, our DNS server wants to use their 2 MX record even though
> that  domain  has  properly  configured  priority  numbers and their 
> primary server is active.

"Use"  the  secondary,  if  it's  the only MX record IMail ever sees =
perfectly valid for IMail, broken in DNS.

"Use"  the  secondary,  even  if the primary MX record was returned to
IMail = broken for Imail, valid for DNS.

> The problem when it does resolve to their 2 MX record, is that server
> does not except email.

i.e., their server is broken, and they're showing it off.

> Our  caching  in Imail has been turned off for years. So the problem
> may  be  in our DNS Server (Simple DNS Plus) where it's not retrying 
> to get the MX record again; but rather using it's cache.

The cache should contain all MX records that were originally returned.
It's not one-at-a-time.

> Sometimes our DNS does pull the primary MX, other times the 2 MX.

i.e., your DNS server is _also_ broken.

> Is this a problem with our DNS? Or does DNS pull any MX it finds (no
> matter the priority?)

It must pull all valid MXes -- how else would it be able to retry?

--Sandy


------------------------------------
Sanford Whiteman, Chief Technologist
Broadleaf Systems, a division of
Cypress Integrated Systems, Inc.
e-mail: [EMAIL PROTECTED]

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