Do you need any endpoint URL to test your workflow outbound message?
Are you curious about the output of outbound message?
Here is the simple method.
An outbound message is a workflow, approval, or milestone action that sends the information you specify to an endpoint you designate, such as an external service. An outbound message sends the data in the specified fields in the form of a SOAP message to the endpoint.
Configure outbound message
1. Enter a name for this outbound message.
2. Enter a unique name to refer to this component in the Force.com API and to prevent naming conflicts for managed package installations.
3. Enter a description for this outbound message.
4. Before giving the endpoint url just go this website www.postbin.org then click the MakePostbin button, a unique url will be generated and then copy the URL, use it as Endpoint in the outbound message
4. Enter an endpoint URL for the recipient of the message. Salesforce sends a SOAP message to this endpoint.
5. Select the Salesforce user to use when sending the message. The chosen user controls data visibility for the message that is sent to the endpoint.
6. Check the Protected Component check box to mark the outbound message as protected. For more information, see the Force.com Quick Reference for Developing Packages.
7. Select Send Session ID if you want the Salesforce session ID included in the outbound message. Include the session ID in your message if you intend to make API calls and you do not want to include a username and password. Sending a username and password is less secure than sending a session ID.
8. Select the fields you want included in the outbound message and click Add.
9. Click Save.
10. To set outbound messages into action, associate them with a workflow rule, approval process, or entitlement process.
11. To check the outbound message just go to endpoint url of your workflow rule, you can able to view your output as SOAP message.
Note:- If the postbin link is doesn't work for you, then use this URL for your testing http://requestb.in/