Logon to gmail webmail account using a browser and select to use 'less secure apps'. If you want to use POP forwarding instead of IMAP then you would also need to select it in webmail account. then in Thunderbird * Menu icon > New Messages > Existing mail account * Enter name * enter full gmail email address * Enter password - same one you use to access webmail * select to Remember password * clickon 'Continue Usually it sets up to use IMAP If you want to use POP you need to select the 'POP option. to change any setting click on 'Manual config' button Once you click to create account, if using IMAP and OAuth then gmail webpage opens to ask you to logon to set up an OAuth token which is auto stored in Thunderbird. It will then be used instead of your password.