system_shutdown_timeout

Since: Version 2025.05.06-b29689af

The functionality described in this section requires version 2025.05.06-b29689af of KumoMTA, or a more recent version.

How long to wait for an in-flight delivery attempt to gracefully complete when the system is being shutdown. Once this timeout is reached, any open sessions will be aborted.

The default value is computed by summing up the per-message-delivery timeout values:

• mail_from_timeout +
• rcpt_to_timeout +
• data_timeout +
• data_dot_timeout

Caution

If you make this value too short you increase the risk duplicate delivery when the sessions are terminated.