Duplicate Check of Email Before Form Submit

[adriscoll]

Hello,

 

I have looked on the forum, but haven't found the answer to this.

 

I have a basic [name, email, phone, event] web form and want to make sure there person is not submitting twice by doing duplicate check of the mail.  I looked at other solutions that suggested setting up unique IDs for each user, but it would be possible for a user to sign up for more then one event.

 

Any info would be helpful. Not a newbie, but not an expert.