Re: Problems sending mail to comcast.net

[John Peacock <jpeacock@rowman.com>]

Bernd Plagge wrote:
> The error message is
> "450_(TEMPFAIL)_comcast.net_requires_valid_sender_domain".
> My understanding is that in the example below the sender domain should
> be "choicenet.ne.jp". Is it correct to conclude that comcast.net has
> problems to validate this domain?

A quick Google shows numerous people having problems with this going back at
least two years.  Here are a couple of things to check:

1) What is the contents of /var/qmail/control/me (standard install location)?
This must be a FQDN that is resolvable through DNS (though the RFC states
specifically that they shouldn't block if it isn't).

2) Make sure you don't have a firewall rule that blocks DNS queries with source
port = 53 (not to be confused with the normal dest port of 53).  Comcast
apparently has used a BIND option in the past that make all outbound queries
from port 53), which can confuse some firewall rules.

3) Can you manually telnet from one of your servers to the Comcast server and
manually try the SMTP transaction and post the response?  Make sure you use a
real e-mail address in the MAIL FROM: line (with a resolvable domain name).

John

-- 
John Peacock
Director of Information Research and Technology
Rowman & Littlefield Publishing Group
4501 Forbes Blvd
Suite H
Lanham, MD 20706
301-459-3366 x.5010
fax 301-429-5747