It is a bug fix release that takes care of the following issues: Thunderbird 45.6.0 was released on December 28, 2016.It fixes several security issues and an issue that caused the system integration dialog to show up on every start of Thunderbird.
One issue, that the message preview pane is not functional after moving or renaming IMAP folders does still exist.Martin Brinkmann is a journalist from Germany who founded Ghacks Technology News Back in 2005.Whatever version of Thunderbird you re-install, it will automatically find and reuse your profile (it contains your mail, address books, settings, saved passwords, add-ons etc.), which is not deleted when you uninstall or reinstall Thunderbird.Its also possible to keep the current version, and do a custom installation of a older version in a different directory to see if your problem is due to the latest version of Thunderbird or not.Correspondents column Correspondents is a new column that is displayed by default that combines sender and recipients.
You can still add the from column back by right-clicking on the header and selecting the option from the menu that opens up.
Thunderbird 45.7.0 was released on January 26, 2017.
It is a release that fixes several issues in the email client including security issues.
If Mozilla Thunderbird refuses to start and complains about another instance or a profile in use instead, the cause may be a stale profile lock left from a crashing instance of Mozilla Thunderbird, for example.
You can remove the file that locks your profile and try to get Mozilla Thunderbird starting again.
I never had the issue before TB 17 and all machines have fast CPU, tons of memory, and SSD storage. Also, if you use the built in "sync", it may be pushing your booksmarks and stuff to the cloud on close.