This really simple Add-on checks if the domain-part of an email is "valid", eg. if the domain can be found via DNS - if not the email address is rejected as invalid.
Validation is done via the bundled version of GitHub - egulias/EmailValidator: PHP Email address validator
					
					
	
		
	
					
					
					Validation is done via the bundled version of GitHub - egulias/EmailValidator: PHP Email address validator