This article describes how you can customize Thunderbird's date and time formats using regional settings or override preferences.

≡ > Preferences > General > "Config Editor":.

• intl.date_time.pattern_override.date_short = yyyy-MM-dd
• intl.date_time.pattern_override.time_short = HH:mm
• intl.date_time.pattern_override.connector_short = {1}'T'{0}

Thunderbird is the free and open source email client by Mozilla Foundation. I have been using it for some years now. Till now the Thunderbird users had to use an extension Enigmail to use GnuPG. Thunderbird 78 now uses a different implementation of OpenPGP called RNP.

Since RNP library still does not support the use of secret key on smartcards, to use Yubikey or any other GnuPG enabled smartcards, we need manually configure Thunderbird with GnuPG. The steps as said are the following :

Z-Sync to Thunderbird Addressbook
Will sync Thunderbird address book to Zentyal, Zarafa, Horde and outlook.com/hotmail.

VCard Addressbook : a new addressbook for Thunderbird based on the VCARD standards

Welcome on the wiki page of the only add-on for Thunderbird and Seamonkey which will add access to you Exchange calendars, contacts and Global Address List [GAL]. It is an add-on for the Lightning. Calendering Add-on and will allow you to communicate with an Exchange 2007, 2010 and 2013 server using the Exchange Web Service [EWS] interface.You can access any Calendar, Task or Contacts folder on the EWS server in an easy way. And also manage your [Out of Office] settings.

sieve - Thunderbird Sieve Addon