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
What’s new in Thunderbird 52.5.0:
Better support for Charter/Spectrum IMAP: Thunderbird will now detect Charter’s IMAP service and send an additional IMAP select command to the server. Check the various preferences ending in “force_select” to see whether auto-detection has discovered this case.
In search folders spanning multiple base folders clicking on a message sometimes marked another message as read
IMAP alerts have been corrected and now show the correct server name in case of connection problems
POP alerts have been corrected and now indicate connection problems in case the configured POP server cannot be found
Various security fixes
Mozilla Thunderbird 52.5.0
Mozilla Thunderbird 17.0.9 ESR（企业版）
Mozilla Thunderbird 3.1.20