Mails getting sent prematurely due to mystery keystroke combination

This has happened to me within eM Client more than once (and on two separate computers), and it just happened again this morning. I’ll be composing an email and then suddenly the window will close and I discover the email is being sent before I’ve finished it.

As far as I’m aware, there are two keystroke combinations that can send a mail without a mouse click:

  1. Alt-S-N, which opens the Message menu, then selects the Send command.

  2. Whatever has been set as the key combination for Send under Settings > General > Shortcuts > Send Mail. By default this is Ctrl+Enter, but I have it deliberately remapped to Ctrl+Alt+Shift+9, the most elaborate and uncomfortable key combination possible. (Having done so, Ctrl+Enter no longer sends an email and I have tested this.)

I don’t know what caused the mail to be prematurely sent this morning, but I am absolutely sure it wasn’t Ctrl+Alt+Shift+9, and pretty sure it wasn’t Alt-S-N either, because I did not see the Message menu opening at the top of the screen. I was in the middle of correcting a misspelled word, and then poof, the mail is in the outbox, getting sent to the recipient with my incomplete, unedited text.

So if I didn’t type Alt-N-S or Ctrl+Alt+Shift+9, but the message was keystroke-sent anyway, there must be some other, undocumented, magic key combination that when accidentally typed mid-message causes the email to be sent.

Does anyone know what this is and/or how to disable it? I never want an email to go out without my explicitly clicking on a button. This is potentially disastrous.

Yes, I know about unsend and send later. Those features could be a safety net against this, but I still want to know how to keep from unintentionally sending email-in-progress from the keyboard.

I also know that in very sensitive situations, a surefire way to prevent it is to keep the recipient’s address at the top of the email body until it’s ready to be sent and only then cut-and-paste it into the To: field.

But again, I should be able to rely on the email client not to send out emails due to some unintentional keystroke combination.