[mu4e bug] Unable to send message with empty body

[jgoerzen]

Describe the bug

I often send myself quick reminders - I just fill in my own address in To, add a subject, and send.

Since 1.12, if I hit C-c C-c (message-send-and-exit) without adding a body, the buffer gets corrupted and I am asked if I want to "Fix continuation lines".

For instance, the buffer looks like this first:

To: jgoerzen@REDACTED
Subject: Test
From: John Goerzen <jgoerzen@REDACTED>
Date: Sun, 14 Apr 2024 08:37:11 -0500
Message-ID: <87zftwhxq0.fsf@REDACTED>
--text follows this line--

Now I hit C-c C-c, and the minibuffer asks "Fix continuation lines?"

And the buffer now looks like this:

From: John Goerzen <jgoerzen@REDACTED>
To: jgoerzen@REDACTED
Subject: Test
Fcc: /home/jgoerzen/REDACTED
User-Agent: mu4e 1.12.3; emacs 29.3
--text follows this line--Date: Sun, 14 Apr 2024 08:38:56 -0500
Message-ID: <87wmp0hxn3.fsf@REDACTED>

Eventually I will get "Failed to send message".

How to Reproduce

Compose as indicated above. It doesn't matter where the point is; C-c C-c will produce the error.

Adding a RET or SPC to the body does not work around the issue. However, if I add even one printable character to the body (eg, 'a'), then it will send fine.

Environment Debian Bookworm, Emacs 29.3

Checklist

• [X] you are running either an 1.8.x/1.10.x release or master (otherwise please upgrade)
• [ ] you can reproduce the problem without 3rd party extensions (including Doom/Evil, various extensions etc.)
• [X] you have read all of the above

Please make sure you all items in the checklist are set/met before filing the ticket. Thank you!

[djcb]

Does this still happen with 1.12.4? Can you repoduce starting from emacs -Q and just mu4e? (I see you didn't check the middle item in the Checklist... is that on purpose?)

[jgoerzen]

Fixed in 1.12.4. Thank you!

(My apologies for forgetting to include the explanation on the middle item; I use Doom and it is quite difficult to separate out my mu4e configuration, but had you not been trivially able to reproduce, I would have gone to that effort)