Using your example with left-to-right domains and needing a delimiter, one could build a URL structure for mail that changes the protocol but not the path. htt

Using your example with left-to-right domains and needing a delimiter, one could build a URL structure for mail that changes the protocol but not the path. https://com.google https://com.google. for the main page https://com.google.mail https://com.google.mail for gmail https://com.google.mail/localpart https://com.google.mail/localpart for one's own gmail account mail://com.gmail/localpart to send mail to what is currently localpart@gmail.com Alternately, we could continue to use '@' and put the localpart first. The URL method of specifying a username or username and password does this for HTTP/HTTPS. http://username:password@com.site/login http://username:password@com.site/login And currently we use mailto:localpart@example.com but we could use mailsend:localpart@com.example instead.