Trying to be clear, so I logged in at www.xxxxx.com/powermessenger_php7
and logged in as the testuser I am currently using, and clicked the link to validate.
The error message then came. And there indeed was a last line containing the information you inserted.
If I have acted correctly, then I confirm that the credentials you placed there are precisely what is inserted in the Admin Backend email settings section for defining the server.
I sincerely hope I have done the right thing.