Thunderbird is a free, open-source, cross-platform application for managing email and news feeds. It is a local (rather than a web-based) email application that is powerful yet easy-to-use. Thunderbird is developed, tested, translated and supported by the folks at Mozilla Corporation and by a group of dedicated volunteers. Thunderbird gives you control and ownership over your email. There are lots of add-ons available for Thunderbird that enable you to extend and customize your email experience.
Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.
An Archive feature similar to the one in GMail
Lightning fast search
Thunderbird 68.1.0 changelog:
Offer to configure Exchange accounts for Office365. A third-party add-on is required for this account type. IMAP still exists as alternative.
Edit tag not working
Write window: “Insert > Characters and Symbols” not working
Moving/dragging messages from “Search Messages” result dialog not working
Command line -compose “attachment=” not working
Custom views not working
Issues with list of content types/actions for incoming attachments
“Learn More” links in Error Console not working
Visual glitches: Quick Filter Bar tag buttons too tall, missing scroll bar on Connection Setting subdialog, LDAP server selection after “New”, “Edit” and “Delete”
Calendar: Parts of CalDAV dialog not working
Calendar: Free/busy information in attendees dialog not displayed/scrolled correctly
Mozilla Thunderbird 68.1.0
Mozilla Thunderbird 52.9.1
Mozilla Thunderbird 17.0.9 ESR（企业版）
Mozilla Thunderbird 3.1.20