I am using Thunderbird (on Windows 10) to access my e-mail on btinternet.com and have used this successfully for years. The BT e-mail has used Yahoo e-mail and is in the process of slowly migrating users onto its own e-mail system, but I am still on Yahoo. Last Saturday (11th July) my TB client failed to logon (error message - 'sending of password did not succeed'), even though nothing has been changed. I know the password is still correct because I can use a browser to logon to BT e-mail using the same password and get to Yahoo e-mail with all my up-to-date e-mails. My TB client settings have not changed. My wife's e-mail has the same setup in TB and has already been migrated from Yahoo to BT's own e-mail (some months ago) - there is no problem with accessing her e-mail using TB client (same settings as mine). I phoned BT support but they could not offer any help and could not tell me when I would be migrated from Yahoo. Something changed last Saturday, either in BT mail server or TB client, to disrupt the normal smooth operation. Has anyone else experienced this problem and/or does anyone have a solution? Thankyou, Robin