Pigeonhole Sieve: Vacation Extension
The Sieve vacation extension (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) 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
}