Oct. 29, 2011
12:45 a.m.
Barry Warsaw writes:
X-Mailman-Version
I think this should be replaced with X-Mailer, or even User-Agent. That's not currently an SMTP header, but I think it should be. And it is in quite widespread use.
This is just the version of Mailman that sent the message. It can lose the X- prefix.
I think that's a bad idea. The version string should go in a *-Agent header, along with the agent's identity.
While I disagree with having Mailman be a User-Agent, I can't actually say there are useful semantics to having a separate List-Agent. Nor do I see a real problem with having multiple User-Agent headers, if multiple agents have handled the message.