Error in Service Pages when trying to create an account
I have the records of all the people of my company in the Persons tab. Email addresses are there for every record. Now when I open service Pages, and click on "No, I am a new SP User", it asks me for the email id, but when I enter an email ID (of a person who is there in HPSD with no account related to him), it gives an error "You are not eligible for Service Pages. You email address is not accepted".
I have attached a screenshot of the error.
Can someone please let me know what the problem could be and how I can resolve it.