User Email Check

Is there a modification that can be made to check an email after it is entered into the email field to see if the user already has an account? The message could be something like, “This email is already a member, please update your profile to apply for xxxx role.” I’m not sure if on the myaccount page, the fields for certain roles are shown (i.e. I have 4 different user registrations and each are different roles) so that they can apply for the role. And I gather, if they just update their profile, I will not get a notification. Frustrating when folks are applying for a position, and they can’t submit because they are already a customer on our site, and their email is the same one they used for applying to be an author or other role in our system. Any work around you can think of for this?