Looking for logging into the Thunderbird Google Popup site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Thunderbird Google Popup site. After that you can login as usual with your login credentials.
https://support.mozilla.org/questions/1157902
https://support.mozilla.org/questions/1204863
https://support.mozilla.org/questions/1166958
https://support.mozilla.org/questions/1213257
https://support.mozilla.org/questions/1196797
https://support.mozilla.org/questions/1201406
https://support.mozilla.org/questions/1228073
https://support.mozilla.org/questions/1166926
http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite
https://productforums.google.com/forum/#!msg/gmail/S1oYixwDHdQ/AxEifu_AAwAJ
https://www.thunderbird-mail.de/forum/thread/76393-anmeldung-mit-gmail-nicht-mehr-m%C3%B6glich-seit-umstellung-auf-neuen-login/
https://www.thunderbird-mail.de/forum/thread/76405-gmail-anmeldung-pop-up-fenster-reagiert-nicht/
https://askubuntu.com/questions/910327/thunderbird-stuck-at-google-sign-in