Clients like Thunderbird are great because you have everything stored locally so you can easily search offline. They also support encrypting and decrypting emails in PGP. However, they seem to have the same limitation as protonmail where you can’t search through encrypted emails.
I know that protonmail can’t just store your key at their server since that would defeat the purpose, so the emails are all ciphertext to them right? But in Thunderbird, you already have the key and decrypt everything all the time. So why can’t you skip the middleman in your local machine and store everything locally in plaintext? It’s not less secure since if your local machine is compromised, your private key is also compromised.
Or at the very least give us the option and have a slightly less secure but much more convenient option.
If you’re in Linux, you can use eCryptfs to setup a private encrypted directory, move the ~/.thunderbird directory into it and just leave a symlink to it in your unencrypted home directory. Then you can store your emails in plain text in the encrypted private directory.
It’s not even complicated to set up: most Linux distributions are setup so that the private directory is automounted upon login: when you’re not logged in, your data at rest is encrypted. It only becomes readable when you’re logged in.
Both my Thunderbird and Firefox directories are stored in my private directory.
This does not answer the question. OP wants to Thunderbird to decrypt PGP mails. Yes, it makes sense to use an encrypting fs, but we are still missing this thunderbird feature.