Maybe there just shouldn't be an "encrypt to others" checkbox. I mean, either you add keys of others or you don't. What's the point of the checkbox? Okay. I guess now you could encrypt to others but not to yourself. But that would still be possible. What wouldn't be possible is to add keys of others and then decide "Nah. I'll just encrypt to myself/with password."

If you only want to encrypt to one key you could do this without warning if you remove the check before "encrypt to others".

As it is now, the checkbox is redundant, it does not have any effect.

If I understand you correctly, you want to remove the checkbox before "Encrypt to others"?

My proposal was to keep the checkbox and make it functional:

• checkbox ticked and no key given for "Encrypt to others": Warning
• checkbox not ticked and no key given for "Encrypt to others": no Warning

Yes thinking about this a bit more the checkbox is as redundant as any warning. The user interface clearly indicates that if you want to encrypt for others that you have to enter a name or email in this group. If the user does not notice that then a warning message or other explicit action will not help but make the user experience for most other users (requiring a click to check the checkbox) worse.