Subject: E-mail address limitations

From: Age Bosma <[email-masked]>
Date: Tue, 21 Jun 2005 15:58:45 +0200

Hi,

Can you tell me, or point me to a resource, what the official specs are 
for an e-mail address? I would like to know what the official 
limitations are if it comes to allowed characters and maximum address 
lenght.
I'm sorry to ask this while there probably are RFC's for this but the 
whole RFC stuff is a bit of a maze to me. They all point to different 
RFC's again and I wasn't able to find one RFC with the complete official 
(easy to understand) specs.

I hope you can help me out.

Cheers,

Age Bosma

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From: John C Klensin <[email-masked]>
Date: Tue, 21 Jun 2005 10:19:57 -0400

If you are trying to use the addresses to send mail over the 
public Internet, RFC2821 contains the authoritative definition.

    john

--On Tuesday, June 21, 2005 15:58 +0200 Age Bosma 
<[email-masked]> wrote:

> Hi,
>
> Can you tell me, or point me to a resource, what the official
> specs are for an e-mail address? I would like to know what the
> official limitations are if it comes to allowed characters and
> maximum address lenght.
> I'm sorry to ask this while there probably are RFC's for this
> but the whole RFC stuff is a bit of a maze to me. They all
> point to different RFC's again and I wasn't able to find one
> RFC with the complete official (easy to understand) specs.
>

---

From: wayne <[email-masked]>
Date: Tue, 21 Jun 2005 10:02:51 -0500

In <379A254FE1C43CBB377A1D2D@[10.56.209.155]> John C Klensin <[email-masked]> writes:

> --On Tuesday, June 21, 2005 15:58 +0200 Age Bosma <[email-masked]> wrote:
>
>> Hi,
>>
> If you are trying to use the addresses to send mail over the public
> Internet, RFC2821 contains the authoritative definition.

Age:

I'll just add a few comments to what John said.

RFC2822 also contains a definition of email addresses (mailbox).  The
two RFCs differ slightly because the involve different parts of the
email system.  RFC2822 includes things like comments which you can put
on the To: line, but which are stripped off by the time the email gets
to the RFC2821 part.

But, of course, the real world requirements of email addresses don't
match the RFC because too many systems out there are broken.

If you are trying to create a well behaved system, then following the
RFC is a very good idea.  If you are trying to create a system that
has to deal with the uglier details of the net, you will just have to
do a lot of experimentation.  "Be conservative with what you generate,
be liberal with what you accept."

-wayne

---

From: Age Bosma <[email-masked]>
Date: Tue, 21 Jun 2005 17:26:42 +0200

> Internet, RFC2821 contains the authoritative definition.

Thank you.
As stated in section 4.5.3.1 the sizes are clear to me now, though 
there's still some confusion about the allowed characters.
I want to make sure which characters are allowed in the local-part and 
domain of an e-mail address. Section 2.3.1 states: "The content is 
textual in nature, expressed using the US-ASCII repertoire [1]." and 
section 4.5.2 states: "The mail data may contain any of the 128 ASCII 
characters.". Does this mean that the control characters are allowed in 
the local-part and domain? Also, what about characters like: "\ / : * ? 
" < > |"? Should these (and others) be allowed?

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Tue, 21 Jun 2005 16:29:23 +0200

While I'm not sure I can deliver on "easy to understand", RFC 2822 section 
3.4.1 is the best official spec we have on what an email address as used in 
Internet mail looks like.

Note that not everything that has an @ in the middle and a domain to the 
right is an email address; it might, for instance, be a "Network Access 
Identifier" defined in RFC 2486.

            Harald

--On 21. juni 2005 15:58 +0200 Age Bosma <[email-masked]> wrote:

> for an e-mail address? I would like to know what the official limitations
> are if it comes to allowed characters and maximum address lenght.