FILTER-PAUSE(8)

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

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

AUTHORS
Joerg Jung <jung@openbsd.org>