What's new in this version:
- Thunderbird will now prompt to compact IMAP folders even if the account is online
- Complete fix of the EFAIL vulnerability: 1) Removing some HTML crafted to carry out an attack. 2) Optionally: Not decrypting subordinate message parts that otherwise might reveal decrypted content to the attacker. Preference mailnews.p7m_subparts_external needs to be set to true for added security.
- Various problems when forwarding messages inline when using "simple" HTML view
- Deleting or detaching attachments corrupted messages under certain circumstances (not working only in Thunderbird version 52.9.0)