unable to log in to Greenby

Please confirm that your settings are correct according to their help page:

https://greenby.com/support/knowledgebase/article/29

I have set up from new in Thunderbird Account Hub with setting you gave me. The connection security set at none gives me a Insecure mail server detected warning. Authentication error, unable to log in to server. Maybe wrong configuration, username or password. I'm unsure about changing password since it works ok with webmail. Of interest, when I log in to webmail I was told by Plusnet to use Madasafish as provider and this works. An observation. Username and password are working ok with webmail. Only thing left is configuration? Regards Sandy