NAME

     filter-pause — smtpd filter to pause on new connections

SYNOPSIS

     filter-pause [-s seconds]

DESCRIPTION

     filter-pause is a filter for smtpd(8) which can be used to pause on new connections before
     emitting the standard initial SMTP greeting.  This is useful to avoid the so called
     “slamming” technique used by some senders of spam mails.

     The options are as follows:

     -s seconds  Set the number of seconds to pause before sending the initial greeting.  The
                 accepted values are withing the range of 1s and 300s.

                 The default seconds value is 5s.

     With filter-pause enabled, smtpd simply waits the specified amount of seconds on each new
     connection.  If the remote server starts sending SMTP commands before the greeting, the
     connection is rejected.  Otherwise, the connection is accepted and normally processed.

SEE ALSO

     filter_api(3), smtpd.conf(5), smtpd(8)

STANDARDS

     J. Klensin, Simple Mail Transfer Protocol, RFC 5321, October 2008.

HISTORY

     The first version of filter-pause was written in 2015.

AUTHORS

     Joerg Jung <jung@openbsd.org>