Mailing List Message #104381
From: Fred Zwarts (KVI) <>
Subject: Does CGP prefer IPv4?
Date: Wed, 7 Aug 2013 09:35:06 +0200
To: <>
A large part of the mail that our server sends out with SMTP, goes to a server that supports both IPv4 and IPv6. Therefore, I would expect that a lot of mail would be sent via IPv6, which is normally preferred. However, in the logs of last month I can find only three messages that are sent via IPv6. All others are sent via IPv4. It looks as if IPV6 is used only if IPv4 fails.
This CGP server runs on a Linux server. When I try from the command level to telnet to port 25 of that MX server, then almost always IPv6 is used. So, the operating system prefers IPv6. I conclude that CGP prefers IPv4. Is that a setting that can be changed?

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