example.com is good because it is explicitly reserved for this purpose and has no MX records. Although very occasionally a service will check for MX records, b

example.com is good because it is explicitly reserved for this purpose and has no MX records. Although very occasionally a service will check for MX records, but that is incredibly uncommon. My go-to email for public WiFi is fuckoff@exmaple.com and have only been denied once (<1%)