Log in to FTP using Windows Explorer with @ in the username
Solution 1:
I set up a TCP server using nc. By using the following URL I got the following output (I greeted and answered the client by hand). The version of Internet Explorer I used was Internet Explorer 6 from modern.ie.
ftp://user%40name:pass%[email protected]
220 hi
USER user@name
331 ok
PASS pass@word
230 ok
opts utf8 on
It looks to me like escaping with %40 works just fine. If it doesn't work in your case, I'd check if there isn't some server problem. Ideally, try to log in with another client just to check your setup. Internet Explorer has no issue supporting percent-encoding.