e-mail-address ::== mailbox | group
group ::== phrase "." [#mailbox] ";"
phrase ::== *(space word space)
mailbox ::== addr-spec | [phrase] route-addr
route-addr ::== "<" [route] addr-spec ">"
route ::== 1#("@" domain) ":"
addr-spec ::== local-part "@" domain
local-part ::== word *("." word)
domain ::== sub-domain *("." sub-domain)
sub-domain ::== domain-ref | domain-literal
domain-ref ::== atom
domain-literal ::== "[" *(dtext | quoted-pair) "]"
atom ::== ALPHA | DIGIT | "!" | "#" | "$" | "%" | "'" | "*"
| "+" | "-" | "=" | "?" | "{" | "}" | "|" | "~"
