Mail-Followup-To (was Re: IDEA License)

Peter Lebbing peter at
Wed Mar 27 19:27:30 CET 2013

On 27/03/13 14:40, Julian H. Stacey wrote:
> I created it, as far as I recall, from my copy direct from Ulrich, 
> which had no Mail-Followup-To

Correct, the problem originated when you replied[1] to Werner's mail[2].
Werner's mail had the following header:

Mail-Followup-To: "Julian H. Stacey" <jhs at>, gnupg-users at

The difference between that line and a simple Reply-to-All is that Werner would
be in the recipient list with the Reply-to-All, and not with the
Mail-Followup-To. Your reply should have only had gnupg-users at and your
manually added CC to Ulrich as recipients, since your MUA would conclude that
you don't need to CC yourself :).

> I'm familiar with Reply-to:  Not familar with Mail-Followup-To:
> What's the difference ?

Because Reply-To didn't really work out in practice for mailing lists, DJB came
up with two "non-canon" mail headers to remove ambiguity from the meaning of the
Reply-To header. He describes it in [3]. Not everybody agrees with his
view/solution, though.

Whether you like the headers Bernstein created or not, it would seem Werner
didn't want to be on the recipient list, which is why I brought it up in my PS.




I use the GNU Privacy Guard (GnuPG) in combination with Enigmail.
You can send me encrypted mail if you want some privacy.
My key is available at <>

More information about the Gnupg-users mailing list