email address specification
The following is the definition of an email address (mailbox) as defined in RFC 822
mailbox = addr-spec ; simple address / phrase route-addr ; name & addr-spec route-addr = "<" [route] addr-spec ">" route = 1#("@" domain) ":" ; path-relative addr-spec = local-part "@" domain ; global address local-part = word *("." word) ; uninterpreted ; case-preserved domain = sub-domain *("." sub-domain) sub-domain = domain-ref / domain-literal domain-ref = atom ; symbolic reference atom = 1*<any CHAR except specials, SPACE and CTLs> phrase = 1*word ; Sequence of words word = atom / quoted-string quoted-string = <"> *(qtext/quoted-pair) <">; Regular qtext or ; quoted chars. qtext = <any CHAR excepting <">, ; => may be folded "\" & CR, and including linear-white-space> quoted-pair = "\" CHAR ; may quote any char LWSP-char = SPACE / HTAB ; semantics = SPACE linear-white-space = 1*([CRLF] LWSP-char) ; semantics = SPACE ; CRLF => folding ; ( Octal, Decimal.) CHAR = <any ASCII character> ; ( 0-177, 0.-127.) ALPHA = <any ASCII alphabetic character> ; (101-132, 65.- 90.) ; (141-172, 97.-122.) DIGIT = <any ASCII decimal digit> ; ( 60- 71, 48.- 57.) CTL = <any ASCII control ; ( 0- 37, 0.- 31.) character and DEL> ; ( 177, 127.) CR = <ASCII CR, carriage return> ; ( 15, 13.) LF = <ASCII LF, linefeed> ; ( 12, 10.) SPACE = <ASCII SP, space> ; ( 40, 32.) HTAB = <ASCII HT, horizontal-tab> ; ( 11, 9.) <"> = <ASCII quote mark> ; ( 42, 34.) CRLF = CR LF
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