Spampd is an SMTP/LMTP server designed to be hooked into the MTA processing chain (e.g. as a content filter). It is written in Perl and uses the Net::Server framework. It is intended to provide spam filtering at the system level (i.e. ususally for all users). If you rely on per-user configuration or per-user Bayes databases, spampd is not for you.

The major advantage of spampd over plain SpamAssassin (both directly and through spamd) is that it doesn't need to load all needed perl modules on every invocation or spawn a C programme for every mail it receives. Compared to using spamc/spamd, spampd can usually provide a 25% performance increase with local-only tests.

The advantage of spampd over amavisd-new is that it uses the original SpamAssassin header tags, which are more verbose than the tags which amavisd-new provides. This allows easier filtering in the mail client and easier tuning of SpamAssassin.