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.
mail://com.gmail/localpart to send mail to what is currently [email protected]
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.
https://com.google. for the main page
https://com.google.mail for gmail
https://com.google.mail/localpart for one's own gmail account
mail://com.gmail/localpart to send mail to what is currently [email protected]
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:[email protected]/login
And currently we use mailto:[email protected] but we could use mailsend:[email protected] instead.