@fallenhitokiri from the article:

This is how it works behind the scenes:

When the recipient is a Gmail user (enterprise or personal), Gmail sends an E2EE email. The email is automatically decrypted in the recipient’s inbox, and the recipient can use Gmail in a familiar way.
When the recipient is not a Gmail user, Gmail sends them an invitation to view the E2EE email in a restricted version of Gmail. The recipient can then use a guest Google Workspace account to securely view and reply to the email.
When the recipient has S/MIME configured, Gmail sends an E2EE email via S/MIME (just like it does today).

This might mean Gmail will send S/MIME (an open standard i think?) emails instead of the “restricted version of Gmail” thing if possible but it’s not clear whether “recipient is not a Gmail user” or “recipient has S/MIME configured” has higher precedence (though only one option makes any sense).

Apparently S/MIME requires one to obtain a certificate from a Certificate Authority to use it… Sounds quite awkward

@kimapr it’s like saying “if the recipient has PGP configured”.
The amount of people having set it up, including large hosting providers (assuming people use their apps / web interface), is barely existent and mostly in the cyber security and enthusiast space from what I’ve seen.

And it’s Google we are talking about. The deprecation timeline starts on release day. “Statistics show there are no external s/mime recipients, so we are focusing on our own client you’ll have to use moving forward”

@kimapr there also seems to be an acme-mail client that works, but yeah, Actalis wouldn’t be my first choice for anything :(