Thunderbird version 78.2.0 is only offered as direct download from thunderbird.net and not as an upgrade from Thunderbird version 68 or earlier.
Thunderbird only supports MailExtensions, users of the Enigmail Add-on should not update to Thunderbird 78.
- OpenPGP Key generation now disabled when there is no default mail account configured
- OpenPGP: Encrypt saved drafts when OpenPGP is enabled
- Twitter search removed
- Calendar: Event summary dialog is now themeable
- MailExtensions: Some APIs now use defineLazyPreferenceGetter in order to benefit from caching