Email Security queue retention and retry times
The Email Security standard retry and retention times, set how long an undelivered email will remain in the email queue. If a connection results in an error message in the
5xx range, the email will be deleted following the official RFC (Request For Comments) standards, and will not be retried. This is different for routes for which a connection cannot be made, or for error messages in the
4xx range: these will be retried until the email is greater than the retention policy. Typically, you see these errors in Email Activity reports.
The retention time for inbound and outbound mail is set to 6 days. An NDR (Non-Delivery Receipt) is not sent back to the remote sender on inbound emails. The retention time for an outbound email is 4 hours. If the retention period does expire befores successful delivery or the remote server replies with a 5xx error code an NDR is sent back to the sender.
The retry time for both inbound and outbound emails is 30 minutes. If multiple routes exist for inbound emails each route is tried and if all fail the email is retried 30 minutes later.