I use a combination of PGP, S/MIME, and cleartext emails depending on the recipient. Those in the Microsoft world tend to prefer S/MIME because it's already integrated, whereas much of the open-source community prefers PGP. And others can't handle signed email because their corporate mail systems break the signatures or worse, treat this as spam.
At the moment I need to keep the recipient's preference in my head. Do they need signed or unsigned mail; do they prefer S/MIME or PGP; etc. As I get older, that stops scaling well 😉 and it would be nice of Thunderbird's address book could remember this for me on a per-contact basis.
There was an add-on that partially achieves this (https://addons.thunderbird.net/en-us/thunderbird/addon/security-settings-from-addr/) but it doesn't remember the PGP vs S/MIME preference. It also stopped working as of TB78. If I recall, this also used to at least partially work in the days of Enigmail, but doesn't seem to have been ported when Thunderbird got native support for PGP and/or the address book UI got revamped.
It'd be really nice if Thunderbird's address book included native support for this preference.
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