Date: Mon, 06 Mar 2017 11:56:29 -0500 From: Quartz <quartz@sneakertech.com> To: FreeBSD questions <freebsd-questions@freebsd.org> Subject: Off topic: smtp HELO question Message-ID: <58BD94BD.9020405@sneakertech.com>
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This isn't directly related to FreeBSD, but I figure many people here probably run it as a mail server so someone might know the answer to this question. By default, if you're behind a NAT, Thunderbird sends your local IP address as part of the 'hello' when connecting to a mail server, which then gets stamped into the header info for all to see as the email is sent down the chain. I'm trying to debug some email issues, and I suspect that this initial header might be part of my problems. I can configure Thunderbird to send an arbitrary string instead of a NAT IP via the mail.smtpserver.smtp*.hello_argument variable, but I'm not 100% sure what I can legitimately put here without getting my emails marked as spam. Does this field have to match the reverse-lookup up of the world-routable external IP that you send the email through, or can it be any arbitrary string that matches a domain name pattern? Can anyone point me to a resource that explains this in depth?
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