Email lookup is only as good as the input you give it: Firstname Lastname and Company Domain. But many places where you may source a lead simply state the company name without a domain. And unfortunately there is no signal place of registry that makes sure companies do not repeat names so getting the exact correct domain name is non-trivial.
That's why we created a Domain name lookup which just requires the company name and its location. In almost all cases one city will not have two companies with the same name being active at the same time period.