mail headers

[Ken Olum <kdo cosmos phy tufts edu>]

Hi, all.  Here's the story about strange things in the from line.

There is a spam-prevention feature called DMARC.  It allows a domain to
declare that only its specified servers are authorized to send mail
claiming to come from users at that domain.  This breaks mailing lists,
because a mailing list message is actually distributed by the list host,
which is generally not one of the authorized servers.  So when a user
sends a message from a domain using DMARC, cosmos can't just send it on
to the list, or many recipients' systems will reject it.  So instead
cosmos modifies the from-line to say that it comes from the list
address, with the user's name and "via Boston-change-ringers".  The
actual address that the message came from will go in the reply-to line,
so replies to sender only will be properly directed.

Messages from domains that don't use DMARC are left alone.

                                        Ken