While Mozilla “suspend” the development of Thunderbird, it continues to work on it, as evidenced by the release of a new version of the e-mail client, which received the serial number 15 and called as Thunderbird 15. By the way, just yesterday the same serial number has been assigned, and the new version of Firefox. An interesting fact is that it is now referred to the program are similar not only in their numbers.

One of the major innovations in the Thunderbird 15 became a redesigned user interface, virtually identical to that in Firefox 15, but allowing for the mail client. The second is the emergence of a large upgrade live chat. So, if you need to quickly contact the person, instead of the traditional E-mail in Thunderbird can use protocols Facebook, Gtalk, IRC, Twitter and XMPP. Instant chat is implemented in the mail client development efforts Instantbird.
Among the smaller-scale features is support for Ubuntu One cloud service for storing attachments and optional Do Not Track, in addition to the features of the web search. Traditionally marked by increasing the stability of the program and to improve its performance, plus solve a number of problems with security.