How to use 'put URL "ftp://..." if username contains @

[runrev260805 at m-r-d.de]

Hi,
 
how can i use the comand 
put URL FTP://username:password@...
if the username already contains a @.
I tried to put the username into a var, but that does not the trick.
 
Is it even possible?
 
Regards,
 
Matthias