''<p>Marty G [[#question-1532526|said]]</p>'' <blockquote> I was wondering if the easiest way to fix this is to delete this account from Thuderbird and re-add it? </blockquote> Probably not. I really can not think of a much worse approach really. Moving from an account that is not working to an account that can not be added because it is not working does not sound like progress. Lets me start at the beginning. Nothing about webmail resembles mail in a mail client. The protocols used, the ports connected to, and often the authentication used are all different. You could best compare your webmail to google search and tell me that webmail and google search are working fine. (gmail web pages and google search share more in common that a mail client does with the gmail website.) You changed the passwords. Did you delete the oAuth tokens for those accounts in the password manager? Thunderbird does not use you password to connect, it uses an oAuth token and it may wall be several passwords ago. They are renewed when the provider decided and are revoked also at their discrettion. So removing them is the only way to ewnsure they are renewed. See https://support.mozilla.org/en-US/kb/password-manager-remember-delete-change-tb You have just probably also completed one of those Google security updates where they ask you yet again to validate something before spamming every email address they have access to with emails advising you changed something. But did you perhaps inadvertently exclude Thunderbird as an approved application for one of the accounts. Or revoke it's access to mail and contacts. Most access problems with Google have nothing to do with Thunderbird with it's default configuration. However. Cookies in Thunderbird become a problem because folk turn them off for some reason and then their oauth updates simply fail. Got to love those we will save your privacy products like ccLeaner See https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20 It is a couple of years old, but the same old problems continue. Folk continue to change default security settings. Does the gmail account still have IMAP and/or POP enable to retrieve mail? https://mail.google.com/mail/u/0/#settings/fwdandpop Have you checked that the google account is allowing Thunderbird? https://myaccount.google.com/connections?continue=https%3A%2F%2Fmyaccount.google.com%2Fsecurity