How many @ symbol can be in an email address?

Question

Is there any rule for having a specified amount of @ symbol in any email id. Just come to my mind if we\'re to check if an email id is valid or not using PHP.

Answer 1

An addr-spec is a specific Internet identifier that contains a locally interpreted string followed by the at-sign character ("@", ASCII value 64) followed by an Internet domain. The locally interpreted string is either a quoted-string or a dot-atom. If the string can be represented as a dot-atom (that is, it contains no characters other than atext characters or "." surrounded by atext characters), then the dot-atom form SHOULD be used and the quoted- string form SHOULD NOT be used. Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.

See :- http://tools.ietf.org/html/rfc5322#section-3.4.1