Thunderbird: Search is not working

Problem: Thunderbird search is not finding the messages you're searching for (blank search results, terms that you know exist in your emails are returning no results, etc)

Solution: Rebuild the Global Database

Close Thunderbird → %APPDATA%\Thunderbird\Profiles → XXXXXX.default → delete "global-messages-db.sqlite"

→ start Thunderbird → wait for indexing to finish rebuilding itself

Check the status of indexing:

Thunderbird won't let you access your Gmail account

Problem: You're trying to set up your Gmail acct in Thunderbird, but it won't accept your username/password and keeps asking you if you're sure it's correct.

Solution:
https://www.google.com/settings/security/lesssecureapps → Enable → Try logging in w/Thunderbird again