Yes, most Linux mailclients that do encryption. If you wish to encrypt an email to alice@example.com, they will use any public key for that address found in your keyring (often by default, but asking for confirmation with a popup). For instance, Claws, KMail and Neomutt all interact with a keyring like this. I think Evolution does. Keyrings usually have extensive command-line functionality, too.
Actually, mailclients interacting with keyrings seemed sufficiently standard that I assumed it would be fairly easy to implement, not much harder than key export to file. But either would be pretty useful and not really much less secure than the DB.
Maybe relabel the “Copy text” button to say “Select and copy” or “Copy or react” or something? Then the user would expect another menu.
Yes, I mean that. Okay, I’ll suggest it for the other clients. EDIT: Done!
And thank you for creating the URL recognition issue and for being, if anything, too responsive to my comments. I need to more clearly distinguish between when I am just mildly astonished by the UI (possibly just because it’s got a skiamorph) and when something is actually malfunctioning.