October 21, 2014

Overriding the Mozilla Thunderbird HELO hostname

Filed under: Internet, Paranoia — Tags: , , , — martin @ 5:23 pm

I found that when connecting through a SOCKS proxy (e.g. SSH dynamic forward), Mozilla Thunderbird tends to leak its local hostname (including the domain of the place where you are at that moment) as a HELO/EHLO header to its SMTP submission server, who then writes it into the first Received-Header.

To avoid this, use about:config and create the following configuration key and value:

mail.smtpserver.default.hello_argument = some-pc

Or whatever hostname you prefer.

Reference: Mozillazine – Replace IP address with name in headers

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