username specification for email system

classic Classic list List threaded Threaded
4 messages Options
Reply | Threaded
Open this post in threaded view
|

username specification for email system

Wesley Peng-3
Hello,

Is there the username specification for email system?
It seems most special characters like ".", "-", "+", "_", "#", "$" are
permitted in the username part.
And even [hidden email] is right (like my sender account).
So I was confused.

Thanks.
Reply | Threaded
Open this post in threaded view
|

Re: username specification for email system

Patrick Proniewski
On 2019-09-05 09:45, Wesley Peng wrote:
> Hello,
>
> Is there the username specification for email system?
> It seems most special characters like ".", "-", "+", "_", "#", "$" are
> permitted in the username part.
> And even [hidden email] is right (like my sender account).
> So I was confused.
>
> Thanks.

Have you tryied the RFC that defines email addresses? (even the space in
allowed: <my [hidden email]> or "my name"@example.com)

patpro
Reply | Threaded
Open this post in threaded view
|

Re: username specification for email system

Bastian Blank-3
In reply to this post by Wesley Peng-3
On Thu, Sep 05, 2019 at 03:45:47PM +0800, Wesley Peng wrote:
> Is there the username specification for email system?

It is called "local-part". And yes, RFC 5321 and 5322 have a pretty
comprehensive spec for it.

The following is a valid e-mail address for example:
"<script>alert('Ohhai')</script>"@43-1.org

Regards,
Bastian

--
It is undignified for a woman to play servant to a man who is not hers.
                -- Spock, "Amok Time", stardate 3372.7
Reply | Threaded
Open this post in threaded view
|

Re: username specification for email system

Wietse Venema
In reply to this post by Wesley Peng-3
Wesley Peng:
> Hello,
>
> Is there the username specification for email system?
> It seems most special characters like ".", "-", "+", "_", "#", "$" are
> permitted in the username part.
> And even [hidden email] is right (like my sender account).
> So I was confused.

Email RFCs allow many localpart forms, but common sense limits that
to a mix of -+_.a-z0-9, leaving all the special characters for use
by the mail system.

        Wietse