When you use Internet Explorer to access a FTP website, and you enter your username and password, and the format of the URL you enter is ftp://username:password@domain, you may receive the following error message:
Windows cannot find ‘ ftp://username:password@domain’. Check the spelling and try again.
If any of these special characters : # ? / \ % are present in the username or the password, you will get that error message!
KB969869 states that this behavior is by design!
What you will have to do is, encode the special characters in the following way:
: as %3A
? as %3F
\ as %5C
% as %25
# as %23
/ as %2F
When you do this, you will be able to successfully access the FTP server!