"Sending of password did not succeed"

[#1]

I am using Thunderbird 3 on Win 7.
I have 3 email accounts, the main one works fine.
I have re-entered the details for the other two with my password and now when I first open the programme I get the error message
Sending of password did not succeed, mail server mail.plus.net responded:Login failed
I don't know if it is that but my Username is surname and for the Username on the other 2 accounts I have entered surname+john and surname+bill
I can't think what else it could be.

[#2]

Try testing your username / password combinations in Webmail.
It might possibly be security settings, but definitely test Webmail first.

[#3]

Quote

I have re-entered the details for the other two with my password

Don't forget that the passwords for the individual e-mail accounts can be different from the main password, it depends what you specified when you created the accounts.