When I contacted Zonelab's Technical Support, I received the following reply from them:
This Information Applies to:
- ZoneAlarm Pro 3.0, 3.1
- ZoneAlarm Plus 3.1
FrontPage or FTP client won't work with ZoneAlarm Pro or ZoneAlarm Plus
1. FTP programs (which are also used through applications such as FrontPage and Internet Explorer) may need to have Passive or PASV mode enabled, if the other machine supports it. This tells the client to use the same port for communication both directions.
Note: TrellixWeb & CSB, by default, have Passive mode enabled.
2. You may also need to add the FTP server to your Trusted Zone. Click on Firewall -> Zones tab -> Add button -> and enter the site by host name, IP, etc. Use any description you want. When you are done, click OK, then click Apply.
3. If none of this helps, you may need to use Medium Internet Security while using FTP. In some cases you may be able to raise it back to High after the original connection has been made; in other cases you may need to stay at Medium during the FTP session.
Setting the Internet security level to medium does not leave you unprotected, as ZoneAlarm, in addition its firewall capabilities, provides protection against hackers through its unique application control feature. Our product only allows applications the user specifically approves to communicate via the Internet. Our two measures of security taken together provide the utmost protection for our users.