Insert Custom Email Headers into an Outbound Email from the ServiceNow InstanceDescription In some situations, it's necessary to insert custom email headers into an email that's generated on, and sent out from, the ServiceNow instance. Procedure If your instance is set up to use your organization's own mail server or a hosted service such as Office 365, it's recommended to set up a rule (using whatever mail server software/service you're using) to add the custom header. If that's not possible, or if you're using the ServiceNow mail infrastructure (the default option) you can use a Business Rule to insert the custom header (tested working on Madrid): Create a Business Rule: Name: "Add Custom Email Headers" (can be whatever you like)When to run: before Insert tickedUpdate ticked Order: 100Advanced Use the following script as an example (replace "X-MyCustomHeader" with the name of the header and current.instance with the variable or literal value that you want in the header: (function executeRule(current, previous /*null when async*/) { if(current.headers.indexOf("X-MyCustomHeader") < 0){ current.headers = "X-MyCustomHeader:" + current.instance + "\n" + current.headers; }})(current, previous); Applicable Versions Tested on Madrid, will most likely work on other versions Additional Information Note that this is technically customization, and out of support scope, and this cannot be guaranteed to always work in a future version of ServiceNow. Credit for the Business Rule code above goes several ServiceNow Community posts on this subject and was also tested as working by a customer who raised a Case on the issue.