When using IIS as an FTP server, the "220-Microsoft FTP service" message is displayed every time you use the default settings. To disable this prompt, you can solve this problem by using the following methods:
1. At a command prompt, change the location to the % SystemRoot %/inetpub/adminscripts folder.
2. At the command prompt, type
Cscript adsutil. vbs Enum msftpsvc , And then press Enter.
3. At the command prompt, type
Cscript adsutil set msftpsvc/number/suppressdefaftpbanner 1 (Where number is the number of the FTP service where you want to disable the default FTP banner), and then press Enter.
NoteIf you have multiple FTP virtual servers, run this command for each virtual FTP server that has a different value for number. when you type the command, do not include a space between msftpsvc/and number.
4. At the command prompt, run the following command to restart the IIS service:
Iisreset
Source: http://support.microsoft.com/kb/826270