>>> "AS" == Adam Sjøgren writes: > Uwe writes: >>> I always thought it was added automatically by a MTA somewhere if you >>> left the To: field blank. I don't think anyone types it in there manually. >> >> Well not gnus. > Like Eric Abrahamsen, I think that this bogus value > "undisclosed-recipients" is inserted by Microsoft Exchange, Gmail or > similar, when there is no To: field. > To test this, I tried composing an email in the Gmail web-interface with > two recipients in Bcc: and nowhere else. The resulting emails arrived > with: > From: Adam Sjøgren <[redacted]@gmail.com> > Subject: Test Bcc only from Gmail > To: undisclosed-recipients:; > Date: Sun, 10 Feb 2019 19:06:20 +0100 > From: Adam Sjøgren <[redacted]@gmail.com> > Subject: Test Bcc only from Gmail > To: undisclosed-recipients:; > Date: Sun, 10 Feb 2019 19:06:20 +0100 > So Gmail inserts the bogus value "undisclosed-recipients:;" in To: when > you only put recipients in the Bcc field and leave To and Cc empty. I use gnus and gmail smtp mail server run your experiment and received From: Uwe Brauer Subject: test undisclosed Date: Mon, 11 Feb 2019 20:01:07 +0100 (2 minutes, 3 seconds ago) Reply-To: Uwe Brauer So no undisclosed-recipients:; is inserted. Sort of odd?