The course of action became clear when I remembered something from earlier in the summer. For a couple weeks, most mail that the list or I received from AOL (and I can't cut them off: 1/3 of my list's subscriptions are at AOL addresses) and one piece from mediaone.net came in without RFC822 From: fields. When that happened, I had procmail generate a From: header with the address from the Unix From_ line. Now that the list is on a site running true sendmail and the existence of the owner-listname alias is clobbering the From_ lines, I'm using the From: ad- dress to correct the From_ line. If a post comes in with no From: header again, the owner-listname alias will clobber the From_ information, there is no Return-Path: (as I said in an earlier post), and while I can find the originating site from the Received: headers I'll have no way to learn the sender's logname except from a signature in the body. That would allow any AOL user to spoof any other AOL user -- maybe a big laugh to those of you who get only trouble from America OnLine but a major disaster for my list. So unless reconfiguring sendmail to add Return-Path: salvages the real enve- lope sender address -- and that's a sendmail question, not a list management question, so I'll ask it elsewhere -- the owner-listname alias is dangerous, and I've asked the sysadmin to remove it after the last mail to it has a chance to trickle in. I'm now using listname-owner as the envelope sender of list distributions.
