The SPF filter is an addition that can be used to filter bulk email sites that operate on behalf of other organisations and are often the source of bulk advertising spam. They do not usually appear on spam blacklists because they operate of a supposedly opt-in basis. However, most recipients of the emails never subscribed to the services offered.
Adding an SPF filter allows the administrator to block all emails that use specific SPF options to validate themselves. This results in an effective network ban, regardless of email address, on the bulk emailing service. As long as they have a consistent SPF record, you can block them.
However, this should be used with caution as it is possible that a service for which you want emails it using the same service as one that you want to ban, in which case this mechanism should not be used.
SPF filters are added to a text file in the FTGate program folder (spfkill.txt). In order to add/maintain this list you will need to have administrator rights to the machine running FTGate. You will also need to become familiar with the SPF record structure and locating/interpreting the record form the log files.
You can block the name of the SPF record and the IP4 include blocks.
The log contains the line:
SPF Record:(bad-domain.com) v=spf1 ip4:188.8.131.52/22 ip4:184.108.40.206/24-all
You can add the entries:
to the spfkill.txt file and you will then block those entries.
The spfkill.txt file is reloaded periodically so changes may not take effect immediately. You can restart FTGate to force them to be loaded.