In general Sphera doesn't recommend using IE as an FTP client, as it does not fully implement the FTP protocol and does not always work properly.
We have a specific problem with our username which has the '@' character.
To login to an ftp site IE uses the following conventions: ftp://:@.
The '@' in the user name confuses this convention. The workaround is to use '%40' instead of '@' in the username.
For example, if the ftp login details are :
Then the proper way to login to the ftp using IE would be: ftp://john%40vds.com:firstname.lastname@example.org