Local queue

Queue module buffers messages on disk and retries delivery multiple times to another target to ensure reliable delivery.

It is also responsible for generation of DSN messages in case of delivery failures.


First argument specifies directory to use for storage. Relative paths are relative to the StateDirectory.

Configuration directives

target.queue {
    target remote
    location ...
    max_parallelism 16
    max_tries 4
    bounce {
        destination example.org {
            deliver_to &local_mailboxes
        default_destination {

    autogenerated_msg_domain example.org
    debug no

Syntax: target block_name
Default: not specified


Delivery target to use for final delivery.

Syntax: location directory
Default: StateDirectory/configuration_block_name

File system directory to use to store queued messages. Relative paths are relative to the StateDirectory.

Syntax: max_parallelism integer
Default: 16

Start up to integer goroutines for message processing. Basically, this option limits amount of messages tried to be delivered concurrently.

Syntax: max_tries integer
Default: 20

Attempt delivery up to integer times. Note that no more attempts will be done is permanent error occured during previous attempt.

Delay before the next attempt will be increased exponentally using the following formula: 15mins * 1.2 ^ (n - 1) where n is the attempt number. This gives you approximately the following sequence of delays: 18mins, 21mins, 25mins, 31mins, 37mins, 44mins, 53mins, 64mins, ...

Syntax: bounce { ... }
Default: not specified

This configuration contains pipeline configuration to be used for generated DSN (Delivery Status Notifiaction) messages.

If this is block is not present in configuration, DSNs will not be generated. Note, however, this is not what you want most of the time.

Syntax: autogenerated_msg_domain domain
Default: global directive value

Domain to use in sender address for DSNs. Should be specified too if 'bounce' block is specified.

Syntax: debug boolean
Default: no

Enable verbose logging.