This update for MozillaThunderbird fixes the following issues:
Mozilla Thunderbird 78.6.1
changed: MailExtensions: browserAction, composeAction, and
messageDisplayAction toolbar buttons now support label and
default_label properties (bmo#1583478)
fixed: Running a quicksearch that returned no results did not
offer to re-run as a global search (bmo#1663153)
fixed: Message search toolbar fixes (bmo#1681010)
fixed: Very long subject lines distorted the message compose
and display windows, making them unusable (bmo#77806)
fixed: Compose window: Recipient addresses that had not yet
been autocompleted were lost when clicking Send button
(bmo#1674054)
fixed: Compose window: New message is no longer marked as
'changed' just from tabbing out of the recipient field
without editing anything (bmo#1681389)
fixed: Account autodiscover fixes when using MS Exchange
servers (bmo#1679759)
fixed: LDAP address book stability fix (bmo#1680914)
fixed: Messages with invalid vcard attachments were not
marked as read when viewed in the preview window
(bmo#1680468)
fixed: Chat: Could not add TLS certificate exceptions for
XMPP connections (bmo#1590471)
fixed: Calendar: System timezone was not always properly
detected (bmo#1678839)
fixed: Calendar: Descriptions were sometimes blank when
editing a single occurrence of a repeating event
(bmo#1664731)
fixed: Various printing bugfixes (bmo#1676166)
fixed: Visual consistency and theme improvements
(bmo#1682808)
MFSA 2021-02 (bsc#1180623)
CVE-2020-16044 (bmo#1683964)
Use-after-free write when handling a malicious COOKIE-ECHO
SCTP chunk