Can not connect to email server

[#1]

Hello I I have an amazon kindle and obviously I have successfully logged in with my password as in here, Kindle tells me I  have an authentication problem to Plusnet -JTGM -24 this service I assume. How can I solve this problem please?

[#2]

Hi there, can you advise what it is you are accessing when seeing this message (ie a browser, the kindle's settings etc), if possible could you also send us a screenshot of this error? - Lauren