When trying to add my email address it errors out

I have an email address with a custom domain name and when I try to add it I get this error code:

• The email address provided is not from an accepted host.

I assumed that you can only use common email domain names such as gmail.com and that worked but I would like to use my normal email address not a random gmail account.

Would it be possible for the domain name to be alow listed by an admin?