How-to remove the port 25 restriction on your EC2 instance

Introduction

By default, Amazon blocks port 25 outbound on EC2 instances. As a result, email will be unable to be sent outbound unless a smart host is configured. 

Procedure

You can use the following link to send a request to Amazon to lift the restriction on port 25:

How do I remove the restriction on port 25 from my EC2 instance?

Additional Information

Many providers block port 25 by default to prevent spam from being sent from their servers:

Why is port 25 blocked?