The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Thursday, February 03, 2000

More than you ever wanted to know about Reply-To munging

More info on the email snafu: Rich Lafferty replied with:

Note: The “Reply-To” field is added by the originator and serves to direct replies, whereas the “Return-Path” field is used to identify a path back to the originator. [This is from section 4.3.1 of RFC-822. But see section 4.4.3 for a different interpretation. -Sean]

Although I'm starting to wonder if this isn't symptomatic of a majordomo bug, or at least a design flaw. It would make sense to me to configure Majordomo such that the Reply-To points to the list *unless* the originator added its own Reply-To, in which case it would leave that there. That way, you'd have discussion on the list except when the original poster intended otherwise, which strikes me as something that the original poster might very well want. This would satisfy the objection of lost information (which strikes me as the only thing that isn't a question of preference or user-agent configuration – when majordomo strips a reply-to, it's *gone*) and the objection of encouraging public discussion (in that unless otherwise specified by the originator, the reply is directed to the list).

Pete Turnbull replied with:

Except that mailing lists are not what RFC 822 defined “Reply-to:” for. Its primary purpose is quite different; it's to force a reply to a valid address when the sender's “From:” is not valid.

Quote: “The 'Reply-To' field is added by the originator”

The RFC 822 method would be to set the “From:” field to [mailing list address], and set the “Sender:” field to the name of the person who originated the message (which is exactly the opposite to what majordomo is doing, I notice, but that's perfectly legitimate).

So, where does this get us? Well, I send a message to a mailing list:

From: <>
To: <flamefest@lists.tld>

The mailing list software gets it, and when it sends it out:

From: <flamefest@lists.tld>
Sender: <>
To: <joesixpack@somesite.tld>

But, if for some reason I want replies (to me) to go elsewhere, I send:

From: <>
To: <flamefest@lists.tld>
Reply-To: <sean@randomsite.tld>

And what the mailing list software sends out:

From: <flamefest@lists.tld>
Sender: <>
To: <joesixpack@somesite.tld>
Reply-To: <sean@randomsite.tld>

But we'll see …

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