Added a setting to allow cache expiration to be specified in minutes.
Version 1.0a
Fixed a possible issue with stdout not being completely flushed, stalling the filter
Version 1.0
Separated the Positive and Negative cache timeout
Version 0.9
Handling the NOOP answer correctly instead of just waiting for an error
Version 0.5
Command-line parameter to remove all cached entries on startup (/uncache)
Version 0.4
SMTP commands are logged for debugging. This will be removed or made an option later.
Version 0.3
Domain names can be entered instead of IPs in the database. Resolved IPs are cached internally for 60 seconds, then resolved using gethostbyname for each request, regardless of the TTL value.
Version 0.2
SMTP sockets are now protected by a mutex so only one thread can access a given domain at a given time