NAME
     mopher -- versatile mail filter

DESCRIPTION
     The mail gopher (mopher) is an extension to all mail transfer agents
     (MTAs) that implement the Sendmail Milter API.  It reads a list of rules
     and acts on each incoming mail delivery attempt based on various criteria
     and existing states.  Since the general idea behind mopher is to replace
     the chain of milters that is often consulted by the MTA, mopher's design
     is modular and its language can be extended through a variety of loadable
     mopher modules.

     The following list describes mopher's core features:

     Greylisting
             Mopher supports indiscriminate and selective greylisting.  It
             lists either individual addresses or whole domains (based on
             reverse lookups and rules provided by Mozilla's Public Suffix
             List) and keeps track of all retries by a particular origin.
             Listing domains avoids cases where several load balancing MTAs
             are trying to deliver the same message, while counting retries
             (and acting upon the result) can speed up the inevitable.

     Whitelisting
             Mopher supports whitelisting origins (address or domain) based on
             their amount of successfully delivered messages.  It also tracks
             penpals, which are triplets containing the origin, the sender-
             and the recipient-address.  Whitelisting based on penpals is the
             prefered strategy when dealing with Email providers that host
             large numbers of legitimate users but also significant amounts of
             spammers.

     Tarpitting
             Mopher supports delaying incoming mail delivery attempts.
             Tarpitting, like any other action, can be applied selectively.

     Generic Storage
             All tables kept by mopher are accessed through a generic inter-
             face.  The selection of backends is therefore only limited by the
             amount of available database modules.  Currently, several backend
             modules are provided.

     Custom Logging
             Mopher uses a well structured default log format and allows for
             additional custom logging at any stage, which also includes the
             access to all symbols available at that particular stage.

     Custom Headers
             The injection of custom headers is possible.  Like with custom
             logging, all symbols available at a particular stage are also
             available when defining a custom header and its content.

     Control Socket
             Communication with a running mopher daemon is possible through
             its control socket.  Available actions are currently limited to
             the printing of tables and modifying of greylist items.

     Successfully configuring and running mopher requires a basic understand-
     ing of SMTP and its various stages.  Users are also encouraged to consult
     mopherd.acl(5), in order to get an overview of the basic language and its
     expressions.

     The following list describes mopher's module features:

     Local: Clam AntiVirus
             Support for clamd queries.

     Local: MaxMind GeoIP
             Support for MaxMind GeoLite queries.

     Local: Passive OS Fingerprinting
             Support for p0f queries.

     Local: SpamAssassin
             Support for spamd queries.

     Network: Black- and Whitelists
             Support for DNSBL queries.

     Network: Sender Policy Framework
             Support for SPF queries.

     Backend: Berkeley DB
             Support for legacy BDB storage.

     Backend: MySQL
             Support for MySQL storage.

     Backend: PostgreSQL
             Support for PostgreSQL storage.

     Backend: SQLite3
             Support for SQLite3 storage.

     Note: Third party distributors of binary packages may split a full mopher
     build into several complementary packages in order to make some dependen-
     cies optional.  In such cases, it is possible that some modules are not
     available on your system even though they are listed here.

SEE ALSO
     mopherd(8), mopherctl(8), mopherd.conf(5), mopherd.acl(5)

AUTHORS
     Manuel Badzong, manuel@badzong.com
     Petar Bogdanovic, petar@smokva.net

BUGS
     Any issues related to building, running or configuring mopher can be
     reported at the following location:
           https://github.com/badzong/mopher/issues

     There is also a general discussion mailing-list:
           https://groups.google.com/d/forum/mopher