MC is a console file manager. It supports FTP connections, and is a great alternative to classic ftp client.
However, the default FTP connection format string [username[:password]@]hostname has a drawback of not allowing the use of usernames with ‘@’-symbol in them – which is very common.
One of the solutions is to create a .netrc file with following content(replace all-caps words with your actual credentials)
machine HOSTNAME login USER@HOSTNAME password PASSWORD
or if you want to ask for password every time:
machine HOSTNAME login USER@HOSTNAME
Now, start MC, choose FTP connect, and enter only the hostname. This will also work for console ftp clients like lftp.