Somewhere in the last couple of times I've updated to a new version of elm, it's changed from waiting after editing a message to sending the message immediately. It puts up a screen giving you the options for editing headers and cancelling the message and stuff, but the default action if you hit an option it doesn't recognise is not "beep" (as it was previously), it's "send the message".
And somehow it hallucinates occasional keystrokes that I didn't send. When these performed the "beep" command, that was OK. All software sucks, mail software sucks more than most, but I have found that for me "elm" has up to now sucked mostly in ways I can hate in silence. But this is just too hateful. I need to find new mail software to hate.