Is "@" a valid char for <LoginUserName> ?

[eas...@absamail.co.za]

Hi,

My theory is that the login procedure for BBSs was taken over by ISPs.
Ie. a name selected by the user was allowed as his <LoginUserName>,
unless this <LoginUserName> had already been allocated.

These days ISP users often have 4 different strings:
1. <LoginUserName>
2. <LoginPaswrd>
3. <emailUserName>
4. <emailPaswrd>

Whereas the RFC clearly states that "@" has a special meaning for
URLs, ie. for the <emailUserName>, it does not deal with the
logingIn procedure.

Ie. "jo...@ibi.co.za" would be a permitted <LoginUserName>

The OS which I use assumes that "@" will never be in the
<LoginUserName>, and uses it the separate the <LoginUserName>.

My latest ISP allocated a <LoginUserName> with "@" in it, so
this breaks the OS. I'm looking for evidence that the OS's utility
needs to be changed.

Thanks for any advice,
Chris Glur.