CIRCLE WITH A DOT

@rbos Yes. I'm going back a ways, but I first implemented it on a sendmail and Cyrus IMAP setup. It involved a couple of minor changes on the sendmail side (essentially ignoring the plus part during incoming address rewriting and then adding it back to the final delivery address); and a permission change, adding the p permission to mail folders to allow delivery on the Cyrus side. I'm fairly sure we did it at my next employer too, with exim and Cyrus. It Just Worked for every user

@rbos Oh it works to the extent that adding a plus part has no effect on delivery to the inbox (I also tested). What I remember (and what I certainly set up when I was adminning email) was that user+foo@example.com would look for a mail folder belonging to user and called foo, and deliver direct into that mail folder if it existed.

@rbos @ericphelps Interesting: I could have sworn that once upon a time, if there was a mailbox name corresponding to the part after the +, Google would deliver mail into that mailbox. Experiment says no. Maybe I'm confusing it with email setups I tended to in my sysadmin days, where I made sure that worked.