See [Configuring your Gmail account] for instructions on how to configure Gmail for access with "less secure apps"...

Thank you Onno for your help. It was indeed this security setting that caused the problem. Everything back to work again.

ruudj said

Tbird worked fine with my standard Gmail account. As from today it keeps on asking for my gmail password at login. Although email address and password are all filled correctly it keeps asking for a new password. What is wrong here?

Enabling on Google "Less secure apps" to access your email account opens the doors to hacks. I've disabled this function and also enabled Google "2 step verification" to prevent hacks even if they get ones password; only registered devices can sign in no others. Unfortunately Tbird is no good for Gmail anymore so beware of being able to work around the system options to make it work. I have noticed that most if not all competing email clients to Google are listed as unsecure, and wonder if the Chrome browser with built in client is the only option available now?

You have been drinking too much Google Koolaid.

Onno Ekker said

See [Configuring your Gmail account] for instructions on how to configure Gmail for access with "less secure apps"...

Airmail said

You have been drinking too much Google Koolaid.

TBird is no longer updated, read Googles support page listed below and educate yourself.

Allow less secure apps access to your Google account: https://support.google.com/accounts/answer/6010255

I think Windows Free Live Desktop Mail Client is now the better option?

Thunderbird developers are working on support for Google's OAuth2 authentication. In the meantime you can configure Google to support "less secure" applications like Thunderbird