What's is a dead letter queue?

From the docs:

The Force.com Platform provides an outbound messaging system that lets you configure the platform to send SOAP-based messages to a web service endpoint on the internet. These messages are typically triggered by workflow rules on persisted objects. Although outbound messaging is asynchronous (each SOAP message can contain up to 100 notifications of changes), it also allows easy callbacks to the Force.com platform using the Force.com Soap API, as outbound messages contain the enterprise/partner endpoint URLs, as well a session ID token.

The outbound messaging service also features a retry mechanism on failed outbound messages, a retry system (it retries for 24 hours), a dead letter queue and a monitor (Setup -> Monitoring -> Outbound Messages).

It also provides many mechanisms that support security: HTTP/S and X.509 certificates provide the bulk of the security. You can also verify the IP address of the outbound messages to ensure that they come from salesforce.com servers, and the payload includes your organization ID, which you can verify.

1 Answer 1


TL;DR - your message cannot be delivered and the system stops trying. I don't believe you can access Salesforce's Dead Letter Queue for Outbound Messages.

To understand what a Dead Letter Queue is, you may wish to read the definition on Wikepedia:

In message queueing the dead letter queue is a service implementation to store messages that meet one or more of the following criteria :

  • Message that is sent to a queue that does not exist.[1][2]
  • Queue length limit exceeded.
  • Message length limit exceeded.
  • Message is rejected by another queue exchange.[3]
  • Message reaches a threshold read counter number, because it is not consumed. >- Sometimes this is called a "back out queue".

Dead letter queue storing of these messages allows developers to look for common patterns and potential software problems.[4]

  • 1
    I'm sorry - I clearly cannot google. Commented Mar 6, 2018 at 1:40

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