See https://wiki.mozilla.org/Thunderbird:OpenPGP:Smartcards

I've seen that page, but I may be not entirely understanding. I don't want a smartcard auth, I only need thunderbird to request signing using my gpg instead of its own, is it possible?

I don't want a smartcard auth, I only need thunderbird to request signing using my gpg instead of its own

Yes, that's why I did suggest you read the article - all of it. You can follow the suggestion or not, up to you.

I read the whole article, every paragraph. However, I keep hitting the issue.

I do have gpgme installed. I went to account settings -> end-to-end encryption -> add key -> from external -> pasted there last 16 characters of my key's fingerprint. Still same problem. (I also tried first 16 characters, the whole fingerprint, and key ID).

Check the Thunderbird Error Console (Ctrl-Shift-J). There should be a message like this: Successfully loaded optional OpenPGP library libgpgme.so.11 from system's standard library locations

Do you see that?

You'll also need a working Pinentry for entering your private key's passphrase.

I have

> Successfully loaded optional OpenPGP library libgpgme.so from system's standard library locations

I do have pinentry

Here's full logs from Ctrl+Shift+j (attached the screenshot too since it is probably more readable)

``` 1674338016947 addons.xpi WARN Checking /nix/store/995d7b91g74y4smyapi3lkp4nsb2mw68-thunderbird-102.6.0/lib/thunderbird/distribution/extensions for addons Successfully loaded OpenPGP library librnp.so version 0.16+git20220124.f06439f7.MZLA from /nix/store/995d7b91g74y4smyapi3lkp4nsb2mw68-thunderbird-102.6.0/lib/thunderbird/librnp.so RNPLib.jsm:100:15 Found 0 public keys and 0 secret keys (0 protected, 0 unprotected) RNPLib.jsm:301:15 Successfully loaded optional OpenPGP library libgpgme.so from system's standard library locations GPGMELib.jsm:69:13 gpgme version: 1.18.0-unknown GPGMELib.jsm:241:15 services.settings: Failed to load last_modified.json: TypeError: NetworkError when attempting to fetch resource. Utils.jsm:330 Layout was forced before the page was fully loaded. If stylesheets are not yet loaded this may cause a flash of unstyled content. aboutconfig.js:470:9 Trying to load /nix/store/995d7b91g74y4smyapi3lkp4nsb2mw68-thunderbird-102.6.0/lib/thunderbird/libotr.so OTRLib.jsm:64:11 Trying to load libotr.so from system's standard library locations OTRLib.jsm:64:11 Trying to load libotr.so.5 from system's standard library locations OTRLib.jsm:64:11 Trying to load libotr.so from system's standard library locations OTRLib.jsm:64:11 Error: Cannot load required OTR library

   loadExternalOTRLib resource:///modules/OTRLib.jsm:109
   init resource:///modules/OTRLib.jsm:115
   once resource:///modules/OTR.jsm:118
   init resource:///modules/OTR.jsm:139
   init resource:///modules/OTRUI.jsm:256

OTR.jsm:127:15 tb.account.size_on_disk - Truncating float/double number. ```

Could it be the problem with OTR?

Found 0 public keys and 0 secret keys

Did you import the corresponding public key into Thunderbird as described in the article?

Could it be the problem with OTR?

No.

Ok so, apparently, when I import the **public** key through openpgp key manager, I should press Not accept when it prompts. Now it works. Thank you so much for the help!

apparently, when I import the **public** key through openpgp key manager, I should press Not accept when it prompts.

I somehow doubt you can send encrypted messages properly when not accepting your own public key.