The message below is from the admin at the school where our
mail is being returned undeliverable. What do you think ?

-----Original Message-----
From: James Ford [mailto:[EMAIL PROTECTED]]
Sent: Friday, December 14, 2001 1:21 PM
To: Cris Porter
Subject: Re: FW: [IMail Forum] FW: Undeliverable Mail #1


On Fri, 14 Dec 2001, Cris Porter wrote:

>I going to send you a few msgs containing a conversation
>I've had ongoing at the I-mail forum about our undeliverable messages.
>Let me know what you think.

Arcadia (all schools under "tusc.k12.al.us" for that matter) have three MX
records for their domains:

arc.tusc.k12.al.us.     4H IN MX        5 www.arcadia.tusc.k12.al.us.
arc.tusc.k12.al.us.     4H IN MX        10 arcadia.tusc.k12.al.us.
arc.tusc.k12.al.us.     4H IN MX        20 ns1.tusc.k12.al.us.

The first two MX records will never be accessible (207.79.237.11) via SMTP
(port 25) or POP (port 110) - this is by design.  Mailers will (should)
query a DNS server, get a listing of all MX records for a site, and
attempt to rotate thru the MX records for delivery.

>From your log snippets, it appears that your mailer first attempts to
connect to www.arc.tusc.k12.al.us (port 25 is blocked) and upon not
getting an SMTP connection just quits.

>20011212 095516 127.0.0.1       SMTP (2016) Connect arc.tusc.k12.al.us
>[207.79.237.11:25] (1)
>20011212 095518 127.0.0.1       SMTP (2016) 421 SMTP service not available,
>closing transmission channel

Any attempt to connect to port 25 (ie, telnet www.arc.tusc.k12.al.us 25)
will not happen - it would be the same as attempting to telnet to an IP
address with no machine on it.  Thus the 421 error is _not_ being returned
by www.arc.tusc.k12.al.us but rather by something else - I suspect the
program running at 127.0.0.1

If a connection fails then 127.0.0.1 should query DNS, see all MX records
involved, and round-robin down until all MX records have been tried. Your
localhost guy (127.0.0.1) closes the initial connection attempt without
attempting to go to any other MX records.

>> X-RBL-Warning: This E-mail was sent from a mail server with no reverse
DNS
>> entry.

Any "X-insert-header-here" is a descriptive header only.  People use it
for filtering but it has nothing to do with RFC2821 (replaces RFC821) and
RFC2822 (replaced RFC822).





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