Configuration could not be verified - is the username or password wrong?

Configuration could not be verified - is the username or password wrong?

Hi guys,  I've recently created an email account in my email free service.  I can use the account in online and it is working properly. But when I tried to open it in Mozilla Thunderbird in Ubuntu OS I am getting an error saying:

"Configuration could not be verified - is the username or password wrong? "

I entered the correct username and password but the error is consistent. I changed the password to a simple one but still I am getting the same error

May I know how to sort this issue ?