I am finding that Thunderbird 52.5.0 is not displaying PGP encrypted
mail messages properly. I am seeing two issues:
I consistently get "Enigmail Error - No Valid armored OpenPGP data block
found" on various inbound (inbox) encrypted messages. If i open another
mail client, before touching the mail item in Thunderbird, like outlook,
where both mail clients are using IMAP, click on the item, see it
decrypt the mail item in outlook, then move the mouse to another outlook
mail item, whilst keeping Thunderbird open, i see Thunderbird update the
(same) encrypted mail item, to now include the missing GPG datablock
attachment, and then Thunderbird can open and decrypt the message.
Additionally, with some encrypted mail items, I get the decrypted
message shown in the main Thunderbird Inbox view, but when I double
click on the mail item to a separate tab, get an empty tab. Close the
empty tab and re-open the same message - which then displays the
decrypted mail item correctly.