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From: jason on 29 Oct 2007 13:34
Is the percentage "%" valid in email addresses? So for example if i
have some%one(a)domain.com would this be valid. I'm trying to write an e-
mail application and according to RFC 2822 this e-mail would be
valid.

Section of RFC 2822
atext = ALPHA / DIGIT / ; Any character except
controls,
"!" / "#" / ; SP, and specials.
"$" / "%" / ; Used for atoms
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"


Though some e-mail clients interpret this as invalid.

Any advice welcome.

From: Ralf Hildebrandt on 29 Oct 2007 13:57
On 2007-10-29, jason(a)ouyt.com <jason(a)ouyt.com> wrote:
> Is the percentage "%" valid in email addresses?

Yes.
But nobody uses this anymore.

--
Ralf Hildebrandt (i.A. des IT-Zentrums) Ralf.Hildebrandt(a)charite.de
Charite - Universitätsmedizin Berlin Tel. +49 (0)30-450 570-155
Gemeinsame Einrichtung von FU- und HU-Berlin Fax. +49 (0)30-450 570-962
IT-Zentrum Standort CBF send no mail to plonk(a)charite.de
From: D. Stussy on 29 Oct 2007 15:23
<jason(a)ouyt.com> wrote in message
news:1193679290.183135.271510(a)k79g2000hse.googlegroups.com...
> Is the percentage "%" valid in email addresses? So for example if i
> have some%one(a)domain.com would this be valid. I'm trying to write an e-
> mail application and according to RFC 2822 this e-mail would be
> valid.
> ...

Yes, it is valid. However, note that it historically has a special meaning
as an operator.

From: John L on 29 Oct 2007 21:56
>Is the percentage "%" valid in email addresses?

Language lawyer answer: of course it is, that's what the RFC says.

Real life answer: for a long long time, sendmail rewrote mail to a%b@c
-> a@b, from back in olden days when you had to stuff mail through
gateways to get it delivered. Then spam showed up, and the percent
hack was grossly abused to relay spam.

So the reality is that if you try to send mail to an address with a
percent in it, a fair number of places will just reject it. Unless
you like wearing a "kick me" sign, don't use it. Most addresses with
percents are now lame attempts at spamming, so you won't be doing
anyone any favors by accepting them.

Incidentally, exclamation point has roughly the same problem, due to
its historic use in uucp gateways. For a long time, the way to get
mail to me from the Internet was ima!johnl(a)CCA.



From: Kjetil Torgrim Homme on 30 Oct 2007 08:39
[John L]:
>
> >Is the percentage "%" valid in email addresses?
> [...]
> So the reality is that if you try to send mail to an address with
> a percent in it, a fair number of places will just reject it.
> Unless you like wearing a "kick me" sign, don't use it. Most
> addresses with percents are now lame attempts at spamming, so you
> won't be doing anyone any favors by accepting them.

good advice, but I understood the question to come from someone
validating e-mail addresses, e.g. in a client or a web form. in my
opinion, such validation should make no value judgements on the
cleverness of the address. some people may actually be using UUCP
style routing still, and you shouldn't care -- the meaning of the
local part is nobody's business other than the server handling the
domain.
--
Kjetil T.
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