>1) Do not allow any space characters or any of the following characters: >> >< >( >) >` apostrophe >! >$ >% >, comma >\ >" double quote >; semicolon >: colon >[ >] > >2) Do not allow the character string before the @ to begin or end with one or more periods. However it is ok for this string to contain periods. >3) Do not allow the character string before the @ to begin with one or more hyphens. However it is ok for this string to contain and end with hyphens. >4) Do not allow more than one “@” character. >5) Only allow between 1 and 63 valid characters is before the “@”. >6) Note that this means that before the @ sign the alphabet, numbers and the following special characters are ok: >~ tilde ># >^ >& >* >_ underscore >+ >= >? >/ >' single quote >| pipe >{ >} > >7) After the @ sign, only allow the alphabet, numbers, hyphens, and periods. >8) The character following the @ sign must not be a period or a hyphen. >9) After the @ sign, at least one character must be between any two periods. >10) After the @ sign, the second-level domain name (the characters to the left of the last period on the right back to the @ sign or back to a period) must be at least 2 but not more than 63 characters (letters, numbers, and hyphens [but neither the first nor last can be a hyphen]). >11) After the @ sign and after the last period on the right, there must be at least 2 but not more than 6 letters. >>