Help satisfy my curiosity about how e-mail announcement lists work!
February 25, 2011 4:47 PM   Subscribe

Why do e-mails sent to a mailing list look like they're sent to me and CCed to the mailing list?

There's an institution which is loosely affiliated with the university I teach at. I asked to be put on their mailing list so that I could be aware of talks that were going on there.

When I get the emails, forwarded from my .edu e-mail address to gmail, I see the following:


Every time I get these emails, I find myself wondering if they are sent to me and just CCed to everyone else. But of course the world doesn't revolve around me, so it doesn't work this way. What is going on here?

This doesn't actually matter for anything; it's just that this question enters my head once a week and it would be nice to have an answer. I can provide more information on request.

(Oh, if you know enough about me to make a guess about what the institution in question is, you're probably right.)
posted by madcaptenor to Computers & Internet (5 answers total) 1 user marked this as a favorite
It's very likely that everyone gets a copy of the message addressed to them, with the mailing list in the cc field. That way, they can choose to either reply to the original sender, or "reply to all" to the mailing list.
posted by teraflop at 4:49 PM on February 25, 2011

Well, that seems much more reasonable than the "the world revolves around me" scenario.
posted by madcaptenor at 4:50 PM on February 25, 2011

Is there a reply-to field set? There's kind of a holy war about munging that never got resolved; some places change the reply-to to the mailling list, some leave the ML as a CC to prevent not so smart people from reply-all'ing private info to the list.
posted by pwnguin at 5:10 PM on February 25, 2011

I don't see one when I look through the headers. and if I click on "reply" gmail fills in the address as .
posted by madcaptenor at 5:21 PM on February 25, 2011

Mail messages are composed of headers (Subject, To, CC, Received, etc) and a body. Here's the rub: the headers and the body are only important to the clients on each end. When the message travels from server to server, the SMTP protocol treats the whole damn thing as just DATA.

So, I could have this fictional conversation with the SMTP server:
R: 250 OK
R: 250 OK
R: 250 OK
R: 354 End data with CRLF.CRLF
S: To:,
S: From:
S: Subject: haha
S: See the disconnect between how I tell the SMTP server to
S: route the message and how the message says it was routed?
S: .
R: 250 OK
There is nothing that says what appears in the body has to match what is sent to the SMTP server. And, as you've discovered, many clients and list software takes advantage of this fact.
posted by sbutler at 5:25 PM on February 25, 2011 [1 favorite]

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