I have found an article that addresses this in previous versions and it appears to work with 7.1
credentials must be supplied with initial request using syntax ftp://username:password@ftpsite
something more to note on this topic. For firefox and others, we have included the possibility to get and auth popup asking for your creds, whereas IE prevents this based on security settings. Thus the method to embed creds in the URl is the way to go.
I have the same problem, but what happen when i have a user like this email@example.com ???
There is not way to tell the IE to ask the user and password? or can we use a user credential web page to send the credential to the ftp server?