Re: obscure email address formats

Carson Gaspar <[email protected]> Mon, 23 May 2011 15:13:29 -0700
Newsgroups gmane.comp.security.firewalls.wizards
Message-ID <[email protected]>
On 5/23/11 1:30 PM, ArkanoiD wrote:
> Is there any good reason to allow email addresses (in smtp, imap and alikes)
> in any format different from mailbox@fqdn ?
>
> There is plenty of other stuff defined in RFCs and I wonder if anyone really uses it so
> I should *not* just filter it out.

I assume you really mean mailbox@fqdn for the actual address part only, 
but in case you didn't...

mailbox@fqdn isn't enough - you must at _least_ handle full names in the 
address etc. The quoting rules are byzantine, but really required as 
mail clients emit all sorts of stuff.

I don't think there is any reason to support ! or % addressing any more. 
Be careful when you validate "mailbox" so that you allow all legal names 
(unlike !@##$% javascript validators that refuse user+subfolder@fqdn 
addresses).