Enable sender secret key validation

About this article

To enhance the security of our Email Signature Server we have added a feature to validate the authenticity of the sender.

With this feature, the Email Signature Server only processes emails that are sent by the tenant's Exchange Online server.

This feature is disabled by default since it requires the generation of a new security key which needs to be provided as an environment variable in the deployment.

Prerequisites

Changes required in the Exchange Online Admin center

1. Go to [Exchange Online Admin Page] (https://outlook.office365.com/ecp/?rfr=Admin_o365 )
2. Select Mail Flow
3. On the Rules tab select the templafy email signaturesrule
4. Click the pencil Edit icon; the Rule window will appear
   
   
   
   
5. On the Rule window under the Do the following...section click the [+] button
6. Select Modify the message properties... -> Set a message header
7. Click [Enter Text] for the message header and set the header name to Templafy-EmailSignatureServer-Secret
8. Click [Save]
9. Click [Enter Text] for the message value and set the header value to the new GUID value that was created above.
10. Click [Save]
11. Click [Save]to save the changes to the rule

Changes required in the Kubernetes deployment for Client Hosted

1. Navigate to the Resource group containing the templafyemailsignatureserver Kubernetes service
2. Select the Workloads (preview) item under the Kubernetes resources section of the left hand panel
3. Click the email-signature-server-deployment in the main panel
   
   

   
   
   

4. Select the YAML item in the left hand pane of the email-signature-server-deployment Overview

5. Select the JSON tab of the main panel   
   
   
   
   

6. Add the following as an environment variable in the env section, you can place this after office365SmtpServerHostname block:
   

   {
      "name": "templafyEmailSignatureServerSecret",
      "value": "<Your GUID>"
   },

7. Replace the "<Your GUID>" with the the GUID you configured in the Exchange rule above

8. Click the [Review + Save] button

9. Check the ☑Confirm manifest changes checkbox

10. Click the [Save] button