> One of the main reasons I recommend Signal is because there is no plaintext mode to accidentally use.

We were talking about _email_.

If you are really concerned about someone making a mistake and send mail out unencrypted, just send out an attachment with an encrypted pdf. There are many ways to create one.

On Linux/*BSD you can use qpdf to encrypt any pdf. Maybe libroffice has an option to create a encrypted pdf.

> SMTP, the protocol for sending email, rarely enforces TLS (if it’s even supported at all)

FWIW that's being less and less true. Major players like apple now automatically trash mail (I don't remember if it was marked as spam or bounced) if you try to send them a mail without TLS. I recall gmail published something similar for workspace? And I'm sure others will follow/already have, so you can probably also turn that knob for your own servers too and refuse plain mails -- with a bit of luck that'll bounce off some spam..

(This doesn't change the fact that any admin over there can probably read anything you send to someone there, I don't know.)

EDIT: oh, according to this ( https://old.reddit.com/r/crypto/comments/1q4arv5/everything_... ) enabling TLS doesn't check the host name matches anything sane? So TLS doesn't actually bring in anything, wow...

Discussion 3 days ago (8 comments):

https://news.ycombinator.com/item?id=46492810

I remember old XMPP clients had an interface to send different kinds of messages. One was for chats and one was like a message with subject eland so on. When OMEMO arrived I always wondered if that could be used to make a mail-like system, with chats and mail-like conversations with subjects.