ftp, login name with a '@' in the middle

[Roland Illig]

Enrico Weigelt schrieb:
> * Jesús Guerrero <i92guboj at terra.es> wrote:
>> Hello,
>>
>> I contracted a new hosting today and my user name has a '@'
>> in the middle. How can I -well, can I at all?- instruct mc to login
>> with such a name?
> 
> Your hoster is broken. '@' is not a valid character for usernames.

Can you please prove that '@' may not be used in usernames? I couldn't
find it in RFC 959.

Roland