Check the syntax of the email entered, to quickly flag the error to the visitor
Check for disposable or temporary emails
Prevent inquiries from free ESP’s like Gmail, Yahoo, etc (Can be switched on and off)
Prevent inquiries from role-based emails like info@, support@, admin@ etc (Can be switched on and off)
Check MX records to identify invalid emails
Create and maintain your own local whitelist of domains and emails
Create and maintain your own local blacklist of domains and emails