Comcast are now bouncing all mail from servers without rDNS.
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Reporting-MTA: dns;user-0pyhdarrrz
Received-From-MTA: dns;user-0pyhdarrrz
Arrival-Date: Sun, 30 Apr 2006 13:18:58 -0400
Final-Recipient: rfc822;[email protected]
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp;521-EHLO/HELO from sender x04.10.104.230 does not map to user-0pyhdarrrz in DNS
521-sending machine name must be provided as a fully
521-qualified domain via EHLO/HELO command.
521-see section 4.1.1.1 and 4.1.4 of RFC 2821
521 521: Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mailserver does not fill that requirement. For more information, refer to: Discovery Hub - News & Technology
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Comcast is too big an ISP to be ignored, so what are my options?