We had a requirement to send a field from Salesforce object to external System. Hence created a Outbout messaging saying whenever a record is created send the field. But Iam getting the error message in the OB messaging delivery status. Please advise.
Based on the screenshot, it looks like you are definitely sending Outbound Messages (in case you had any doubts...)
I've seen this before, and it's because the external server to which you are sending the Outbound Message is not consuming them. Instead, it's rejecting the message and returning that error.
It could be that you are sending the message to the wrong endpoint, or it could be something wrong with the external server. Either way you will have to work with whoever manages that external server to get to the bottom of it.