Get Record

I've created a script to look-up a person's details based on their email address, which works fine, see below:

if (input.Contact_Email != "--Your Email--")
{
get_record = Support_Users [User_Email == input.Contact_Email];
input.Company = get_record.User_Company;
input.Contact_Name = get_record.User_Name;
input.Department = get_record.User_Dept;
input.Contact_Phone = get_record.User_Phone;
show Support_Required;
}
else
{
alert("You must enter a valid email address...");
}

My issue is, if the email address they enter isn't present, how do I stop hunting for it? I want to be able to pop an Alert saying email not present and stop searching.

Thanks,

Martyn

support