Built-in RegularExpressionValidator email regex

[Guest]

I was just wondering if there is a reason (maybe a RFC requirement?) that the
built in email address regular expression for the RegularExpressionValidator
in ASP.NET doesn't support email aliases ending in a dash.

For example, the following address will not validate:
(e-mail address removed)

Thanks,

-Steven

 

[Karl Seguin]

Steven,
If you are familiar with RFC's, why not just look it up? my typically
answer to this would be to look up the RFC..teach a man how to fish
afterall..

Anyways, I'd still try to help since RFCs are a pain in the rear and I just
spent 10 minutes trying to follow it because I wanted to know as well.

RFC 2822..
addr-spec = local-part "@" domain
so we are interested in local-part

local-part = dot-atom / quoted-string / obs-local-part
we'll look at dot-atom since that's the most common and we don't want to
quote our email adrress

dot-atom = [CFWS] dot-atom-text [CFWS]
ignore the CFWS (folding whitespace w/comments), so we want the
dot-atom-text

dot-atom-text = 1*atext *("." 1*atext)
so we want atext

atext = ALPHA / DIGIT / ; Any character except controls,
"!" / "#" / ; SP, and specials.
"$" / "%" / ; Used for atoms
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
note that dash isn't in the list, but maybe it's under ALPHA

item-name = ALPHA *(["-"] (ALPHA / DIGIT))
BINGO! We have a dash, but if you have a dash, it must clearly be followed
by another ALPHA or Digit

I could have followed that wrong (and there certainly are other paths) but I
think it's right.

hope that hels

Karl

 

[Steven Berkovitz]

Karl,

Thanks for taking the time to explain this.

I guess my next question is (not for you), why is hotmail allowing this?

Steven,
If you are familiar with RFC's, why not just look it up? my typically
answer to this would be to look up the RFC..teach a man how to fish
afterall..

Anyways, I'd still try to help since RFCs are a pain in the rear and I
just spent 10 minutes trying to follow it because I wanted to know as
well.

RFC 2822..
addr-spec = local-part "@" domain
so we are interested in local-part

local-part = dot-atom / quoted-string / obs-local-part
we'll look at dot-atom since that's the most common and we don't want to
quote our email adrress

dot-atom = [CFWS] dot-atom-text [CFWS]
ignore the CFWS (folding whitespace w/comments), so we want the
dot-atom-text

dot-atom-text = 1*atext *("." 1*atext)
so we want atext

atext = ALPHA / DIGIT / ; Any character except controls,
"!" / "#" / ; SP, and specials.
"$" / "%" / ; Used for atoms
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
note that dash isn't in the list, but maybe it's under ALPHA

item-name = ALPHA *(["-"] (ALPHA / DIGIT))
BINGO! We have a dash, but if you have a dash, it must clearly be
followed by another ALPHA or Digit

I could have followed that wrong (and there certainly are other paths) but
I think it's right.

hope that hels

Karl



--
MY ASP.Net tutorials
http://www.openmymind.net/

I was just wondering if there is a reason (maybe a RFC requirement?) that
the
built in email address regular expression for the
RegularExpressionValidator
in ASP.NET doesn't support email aliases ending in a dash.

For example, the following address will not validate:
(e-mail address removed)

Thanks,

-Steven

 

[Karl Seguin]

Well, there is a quoted-string variant to the dot-atom path we explored.
Reading the specs, it's my belief that quoted-string would allow for a
local-addr to be terminated with a - if it's quoted, ala "test-address-"
(with the quotes actually there).


qtext = NO-WS-CTL / ; Non white space controls

%d33 / ; The rest of the US-ASCII
%d35-91 / ; characters not including "\"
%d93-126 ; or the quote character

qcontent = qtext / quoted-pair

quoted-string = [CFWS]
DQUOTE *([FWS] qcontent) [FWS] DQUOTE
[CFWS]a dash is decimal 45, so it falls in the
%d35-91Perhaps that's what hotmail does.Karl-- MY ASP.Net
tutorialshttp://www.openmymind.net/"Steven Berkovitz"

Karl,

Thanks for taking the time to explain this.

I guess my next question is (not for you), why is hotmail allowing this?

Steven,
If you are familiar with RFC's, why not just look it up? my typically
answer to this would be to look up the RFC..teach a man how to fish
afterall..

Anyways, I'd still try to help since RFCs are a pain in the rear and I
just spent 10 minutes trying to follow it because I wanted to know as
well.

RFC 2822..
addr-spec = local-part "@" domain
so we are interested in local-part

local-part = dot-atom / quoted-string / obs-local-part
we'll look at dot-atom since that's the most common and we don't want to
quote our email adrress

dot-atom = [CFWS] dot-atom-text [CFWS]
ignore the CFWS (folding whitespace w/comments), so we want the
dot-atom-text

dot-atom-text = 1*atext *("." 1*atext)
so we want atext

atext = ALPHA / DIGIT / ; Any character except controls,
"!" / "#" / ; SP, and specials.
"$" / "%" / ; Used for atoms
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
note that dash isn't in the list, but maybe it's under ALPHA

item-name = ALPHA *(["-"] (ALPHA / DIGIT))
BINGO! We have a dash, but if you have a dash, it must clearly be
followed by another ALPHA or Digit

I could have followed that wrong (and there certainly are other paths)
but I think it's right.

hope that hels

Karl



--
MY ASP.Net tutorials
http://www.openmymind.net/

I was just wondering if there is a reason (maybe a RFC requirement?) that
the
built in email address regular expression for the
RegularExpressionValidator
in ASP.NET doesn't support email aliases ending in a dash.

For example, the following address will not validate:
(e-mail address removed)

Thanks,

-Steven