What exactly happens when you try to send a message?

Thanks for responding. When I try to send a message, I get "login to server smtp.googlemail.com with [my email address] failed." It prompts me to re-enter my password, which is never accepted. I've verified that I'm using the correct password.

With Oauth authentication, your password for web access does not work. Check the authentication setting for your SMTP server.

It's set to Normal Password.

It needs to be set to Oauth2 to work with Gmail. You may also need to switch to gmail dot com instead of googlemail dot com.

Here are the basics:

- change your security authorization to Oauth2 (do this for the server settings and also for the Outgoing (SMTP) server - two places - remove the password entries for the account (remove the entire entries both incoming and outgoing) - check to ensure that TB is set to accept cookies - Google will then step you through the authentication process for your PC.

David, sorry to be obtuse but could you tell me how to remove the password entries? The instructions I've found on the internet don't work.

First, click the 'show passwords' button. After doing place cursor on the line for incoming and click to highlight and then click the 'Remove' button. Repeat for outgoing server. It's not obvious so you aren't as obtuse as you think you are...  :) It took me awhile to learn it also.

Thanks very much for all your help - much appreciated. Am still looking for the "show passwords" button. I'll be traveling for a few days and will give this another try next week.

Look under Tools>Preferences>Privacy&Security for a button 'saved passwords' - click that and below the listing is a button 'show passwords'