The problem with plus sub-addressing is that it's an MUA feature, and not functionally specified in RFC 5322, which defines email address formats. RFC 5322 3.2.3 lists the following as valid characters for the local-part of an email address:
The definition of sub-addressing is in RFC 5233, "Sieve Email Filtering: Subaddress Extension". That one's pretty obscure, and you always find 5322 if you go looking for the format definition. But of course web developers don't read RFCs, they just copy magickal regexp incantations that they find on the Google.
Winfield
· 10 months ago
This remains one of my biggest usability pet peeves!
All Comments
http://en.wikipedia.org/wiki/E-mail_address#Sub...
The problem with plus sub-addressing is that it's an MUA feature, and not functionally specified in RFC 5322, which defines email address formats. RFC 5322 3.2.3 lists the following as valid characters for the local-part of an email address:
atext = ALPHA / DIGIT / ; Printable US-ASCII
"!" / "#" / ; characters not including
"$" / "%" / ; specials. Used for atoms.
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
The definition of sub-addressing is in RFC 5233, "Sieve Email Filtering: Subaddress Extension". That one's pretty obscure, and you always find 5322 if you go looking for the format definition. But of course web developers don't read RFCs, they just copy magickal regexp incantations that they find on the Google.