<html>
<body>
At 10:38 AM 12/30/2005, Robert La Ferla wrote:<br>
<blockquote type=cite class=cite cite="">I need to set up outgoing mail
on one of my Linux systems. I configured masquerading via sendmail
but I ran into this anti-SPAM measure from Comcast:<br><br>
Diagnostic-Code: SMTP; 550 [PERMFAIL] comcast.net requires valid sender
domain<br><br>
What's the best way to handle this? </blockquote><br><br>
The FQDN for the host you give the SMTP server via "MAIL FROM:"
must be valid. This value is usually exposed as the
"Return-Path:" in email. Check the value against an
external (comcast) DNS, you will need an A record. An MX records
also helps for other providers like verizon.<br><br>
host -tA FQDN dns01.jdc01.pa.comcast.net.<br>
host -tMX FQDN dns01.jdc01.pa.comcast.net.<br><br>
A PTR record never hurts but may be beyond your control.<br><br>
You can test this via telnet. Sample session:<br><br>
telnet smtp.comcast.net. 25<br>
Trying 63.240.77.77...<br>
Connected to
smtp.comcast.net.<br>
Escape character is
'^]'.<br>
220 *...<br>
HELO FQDN<br>
250 smtp.comcast.net<br>
MAIL FROM: <user@FQDN><br>
250 ok<br>
RCPT TO: <robertlaferla@comcast.net><br>
<x-tab> </x-tab>550
[PERMFAIL] comcast.net requires valid sender domain<br>
...<br><br>
That last 550 should be a 250.<br><br>
<br>
<font face="Verdana" size=2> </font> </body>
</html>