SMTP Task 'mail.btinternet.com - Receiving' reported error (0x800CCC92) : 'Your e-mail server rejected your login. Verify your user name and password in your account properties. Under Tools, click E-mail accounts. The server responded: -ERR [AUTH] (#MBR1213) Please verify your account by going to https://login.yahoo.com'
Trying to login on line takes me to a (unsecured) page telling me of suspciiious activity and demanding I change ny pasword to access my e-mail!
Petros, this is a problem that I have also been having. Check your inbox to see if you have any 'Mailer Daemon' messages about failed emails you didn't send. If so, then you're in the same boat I am - someone has spoofed your email address and using that to make their spam seem more like genuine emails, and BT/Yahoo's system is detecting this as 'unusual activity' and flagging your account for a mandatory password change. Expect this to happen about once a day until the spammer moves to another email address, as there is nothing you can do about it and BT/Yahoo is seemingly unwilling or unable to anything about it also.