Notes from a Messy Desk

OK, mostly these are notes just now, as I do a little research for #1350425. I'm trying to figure out what the 'correct' behaviour for an email auto responder is. MailManager has an auto response system which will send out an email when a ticket is submitted, to acknowledge its receipt. I want to get it right.

There are two problems:

• Do you send an automatic response at all? Is there going to be a human being on the other end to receive it, or are you going to wind up spamming a mailing list, creating mailing loops, sending a message that will bounce?


• If you do decide to send a message, who do you send it to? That might sound daft, but there are a number of header fields which indicate who might wish receipt of a message, including ('From', 'Sender', 'Reply-To', 'Return-Path', 'Resent-From').

Currently MailManager will refuse to send a response if any of the following conditions are met:

1. It's a mailing list identified by the existence of any header in ('list-id', 'list-help', 'list-unsubscribe', 'list-owner').


2. The Precedence header is set to one of ('junk', 'bulk', 'list').


3. There is no Return-Path, or Return-Path is empty.


4. The Return-Path starts with any of ('mailer-daemon', 'owner-').

And it will unconditionally send the auto response message to the address in Return-Path. For dropping the message, I agree with everything but point 3 (which I'm not entirely sure about). And I'm not convinced that the algorithm for choosing the reply address is robust enough. So let's start digging into the RFCs.