[Samba] @ signs in usernames/multi-tenant samba

[Joel Reed]

Is there any way to get samba to work with usernames that look like 
email addresses? Perhaps a way to escape the "@" ?

I ask because I'm setting up a samba server with LDAP backend whose sole 
purpose is to share [homes] directories for end-users from multiple 
companies using virtual desktops at a hosting provider. I need to have 
unique logins across these companies and would very much like to use 
email addresses as usernames for this purpose, but alas nothing like 
this seems to work:

smbclient -U "joel.reed\@visn.biz" "//samba1/joel.reed at visn.biz/"

Any advice would be greatly appreciated.

jr