Added prerequisites

Author: danciaclara

self-hosting/govern/configure-dns-email-service.mdx

@@ -6,6 +6,18 @@ description: Configure DNS records to enable automatic conversion of incoming em
 
 This guide explains how to configure DNS settings to enable the [Intake Email](https://docs.plane.so/intake/intake-email) feature for your self-hosted Plane instance. These configurations enable your server to accept messages sent to your project's dedicated Intake address, which are then  converted into work items in your project's Intake section.
 
+## Prerequisites
+
+Ensure that the Plane server allows outbound traffic on the following email-related ports: 25, 465, and 587.
+
+If any of these ports are currently in use, you can free them by running:
+
+    ```bash
+    fuser -k 25/tcp 465/tcp 587/tcp
+    ```
+
+This is necessary for email functionality (e.g., sending invites, notifications) to work properly.
+
 ## Configure DNS records
 
 1. **Create an A Record**  
@@ -91,3 +103,7 @@ Once your DNS records have propagated, test your SMTP connections:
 
     - Verify that the IP address is correct.
     - Ensure your mail subdomain matches the MX record.
+
+## See also
+
+- [Intake Email](https://docs.plane.so/intake/intake-email)