From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 9 Aug 1995 02:59:10 -0400 From: dhog@plan9.cs.su.oz.au dhog@plan9.cs.su.oz.au Subject: Returned mail Topicbox-Message-UUID: 14f87282-eac8-11e9-9e20-41e7f4b1d025 Message-ID: <19950809065910.GX_rVAFkErxvyuQhRwYPE7cpDkHWYXpRwhkPyvYrm8M@z> Greg Nenych wrote: >Mailers have several things to choose from including "From ", "From: ", and >"Reply-To: ". Do (or should) any of them use "Sender: "? No. Note that "From: " and "Reply-To: " are there for the user agent. Bounce messages should never be sent based on these headers. Rather, they should use the SMTP "envelope sender" (yes, I'm assuming we're talking SMTP here). This is frequently stored in the Unix "From " header (YMMV). Some software may put it in the "Return-Path: " header. Mailing list exploders set the envelope sender to the list maintainer, so that bounces go back to the one person able to do anything about them (eg unsubscribe them). Some software throws away the envelope sender and uses the rfc822 From: header instead. This is very bad. It can cause mail loops, resulting in many many bounce messages in everyone's mail box (this has happened on 9fans). A lesser sin is for the mail user agent to generate replies based on the envelope sender. This is usually easier to fix/work around (just replace the user agent :-). >> Fans of Plan 9 _want_ to be able >> to send 8 bit (utf) characters, and most smtp agents will let them (the "cannot" >> in the message is patently false). > >Actually, that's 8/16 bit UTF characters depending on the encoding. I meant full 8 bit chars as opposed to 7 bit ascii... Anyway, enough about mail. Back to Plan 9!