bug#55926: 29.0.50; message.el does not normalize In-Reply-To field from web links

[Ignacio Casso <ignaciocasso@hotmail.com>]

Hello,

I've recently replied to an email in an org mail list thread using the
"Reply To" button in lists.gnu.org/archive/..., and a reader (Max, in
CC) brought to my attention that the thread was broken in Thunderbird
and that it was because the In-Reply-To field was not normalized and had
not angle brackets around the message id.

He suggested me to report it as a mu4e bug, but mu4e is built in top of
message.el, and after disabling mu4e and trying the same with message.el
I got the same result, so I guess it's actually an Emacs bug.

I saw that Lars was the author of message.el so I added him in CC too.

Sorry if my report is not clear enough, or if the bug is actually in the
website reply button, I don't really know much about email technical
details.

To reproduce the bug, you can follow these steps:

1) configure Emacs to open mail links (I don't
remember the exact steps to do so now, but I can check it out),

2) visit
https://lists.gnu.org/archive/html/emacs-orgmode/2022-06/msg00226.html
with your browser

3) Click the button that says "reply via email to Ignacio Casso" at the
end of the message.

4) In the email compose buffer, the In-Reply-To field will look like
this:

In-Reply-To: 
DB6PR0601MB208724FE4A1EB6D98A176F03C6A99@DB6PR0601MB2087.eurprd06.prod.outlook.com

but it should look like this:

In-Reply-To: 
<DB6PR0601MB208724FE4A1EB6D98A176F03C6A99@DB6PR0601MB2087.eurprd06.prod.outlook.com>


Best regards,

Ignacio