Pigeonhole Sieve: Vacation Extension
====================================

The Sieve vacation extension (RFC5230 [http://tools.ietf.org/html/rfc5230/])
defines a mechanism to generate automatic replies to incoming email messages.
It takes various precautions to make sure replies are only sent when
appropriate. Script authors can specify how often replies can be sent to a
particular contact. In the original vacation extension, this interval is
specified in days with a minimum of one day. When more granularity is necessary
and particularly when replies must be sent more frequently than one day, the
vacation-seconds extension (RFC6131 [http://tools.ietf.org/html/rfc5230/]) can
be used. This allows specifying the minimum reply interval in seconds with a
minimum of zero (a reply is then always sent), depending on administrator
configuration.

Configuration
=============

The *vacation* extension is available by default. In contrast, the
*vacation-seconds* extension - which implies the vacation extension when used -
is not available by default and needs to be enabled explicitly by adding it to
the 'sieve_extensions' setting. The configuration also needs to be adjusted
accordingly to allow a non-reply period of less than a day.

The *vacation* and *vacation-seconds* extensions have their own specific
settings. The settings that specify a period (currently all of them) are
specified in *s*(econds), unless followed by a *d*(ay), *h*(our) or *m*(inute)
specifier character.

The following settings can be configured for the vacation extension in the
'plugin' section (default values are indicated):

sieve_vacation_min_period = 1d :
  This specifies the minimum period that can be specified for the :days  and
  :seconds tags of the vacation command. A minimum of 0 indicates that users
  are allowed to make the Sieve interpreter send a vacation response message
  for every incoming message that meets the other reply criteria (refer to
  RFC5230). A value of zero is however not recommended.

sieve_vacation_max_period = 0 :
   This specifies the maximum period that can be specified for the :days tag of
  the vacation command. The configured value must be larger than the
  sieve_vacation_min_period setting. A value of 0 has a special meaning: it
  indicates that there is no upper limit.

sieve_vacation_default_period = 7d :
  This specifies the default period that is used when no :days or :seconds tag
  is specified. The configured value must lie between the
  sieve_vacation_min_period and sieve_vacation_max_period.

Invalid values for the settings above will make the Sieve interpreter log a
warning and revert to the default values.

Example
-------

---%<-------------------------------------------------------------------------
plugin {
  # Use vacation-seconds
  sieve_extensions = +vacation-seconds

  # One hour at minimum
  sieve_vacation_min_period = 1h

  # Ten days default
  sieve_vacation_default_period = 10d

  # Thirty days at maximum
  sieve_vacation_max_period = 30d
}
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2012-01-06 04:42)
