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rjbs (4671)

rjbs
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http://rjbs.manxome.org/
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I'm a Perl coder living in Bethlehem, PA and working Philadelphia. I'm a philosopher and theologan by training, but I was shocked to learn upon my graduation that these skills don't have many associated careers. Now I write code.

Journal of rjbs (4671)

Monday April 23, 2007
10:38 AM

email addressing sucks

[ #33078 ]

I know that most people know how much email addresses suck, but I found this message in Mutt while looking for something else, and I thought it was a nice illustration.

A user of Email::Valid writes:

I was doing some testing with Email::Valid, and I came across this:

$ perl -MEmail::Valid -e "print Email::Valid->address('dave@#%^&*$.com') ? 'yes' : 'no'"` yes $

This prints "yes", and I don't understand why that address would be seen as valid. It doesn't seem to matter what characters are in the domain part of the address, it always gets marked as valid.

I replied:

Let's have a look!

dave@#%^&*$.com

You don't think this should be valid. Let's consult the RFC.

Section 6.1 says that an address must be . That is:

local-part "@" domain

I'm guessing you don't dispute that "dave" is a valid local-part. A must be:

sub-domain *("." sub-domain)

I'm also guessing you don't dispite that "com" is a valid sub- domain. So, is "#%^&*$"? Well, let's see...

sub-domain = domain-ref / domain-literal domain-literal = "[" *(dtext / quoted-pair) "]" domain-ref = atom

There are no square brackets, so there is no domain-literal involved. That means that if "#%^&*$" is a valid atom, it is also a valid domain-ref, and the address matches the addr-spec pattern.

The atom pattern is:

atom = 1*<any CHAR except specials, SPACE and CTLs>

None of those characters are space or control characters. The specials are:

specials = "(" / ")" / "<" / ">" / "@" ; Must be in quoted- / "," / ";" / ":" / "\" / <"> ; string, to use / "." / "[" / "]"

None of them are specials, either! Are you shocked? Don't be! RFC822 sucks!

I hope this helped. Good night! :)

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  • I wonder, could anyone ever actually register such a weird domain name? Because if not, that would be the difference between theoretically, and practically acceptable.
    • Right. In fact, since this email exchange took place, Email::Valid's check that a domain is valid has become more useful, and would reject this. The only default test is for a fqdn, which has lately come to mean a fqdn for a valid internet domain.

      Still, the awful thing is that the address is valid according to 822, just not deliverable on this Earth's internet.
      --
      rjbs