If you use #GnuPG#GPG, and you would like to ensure interoperability with Thunderbird, you might consider to disable the use of #LibrePGP features, by using option --rfc4880 in your configuration (e.g. by adding a line with the word "rfc4880" to your gpg.conf file.)
At this time it is undecided whether future Thunderbird versions will support LibrePGP or the upcoming refresh of the #IETF#OpenPGP specification, or both, or none of them. Hopefully we'll eventually see a new universal standard.
