Flystrike Spam Interrogator allows the user to test e-mail messages before downloading them from the POP server.

A Score based on an Inventory of tests helps the user identify unsolicited messages for remote deletion.

Messages containing abusive or illegal content can be relayed to the appropriate authorities with a set of automatically extracted headers.
A number of pre-written (English and German) abuse reports are provided to help the user.

If desired, each e-mail message can be viewed in original form or as a web document (for HTML). For the latter, pictures and hyperlinks are removed for the protection of the user.

The user can trace the origin of messages; and ban them according to both MD5 Signature and URL pointers. The banning of these elements allows Flystrike to perform auto deletion of e-mail messages if required by the user.

A log of deleted messages allows the user to discover any false positives. A threat list is available that allows the user to enter e-mails associated with particular worms or incorrigible nuisances; messages from those on the threat list are auto-deleted from the remote server before the conventional interrogation is performed.

A valuable feature of Flystrike is its use of a harmless test virus to ensure that the user has correctly configured the anti-virus software used in conjunction with Flystrike.