Service · EC2 Networking

Open outbound port 25 on your EC2 instance

AWS blocks port 25 by default on every EC2 instance to prevent spam abuse. If you run a mail server, SMTP relay, or an app that sends email directly from EC2, this port needs to be opened through an official request to AWS Support.

EC2 Port 25 Unblock Request Reverse DNS / PTR Record All AWS Regions

What makes a port 25 request get approved?

AWS Support reviews every port 25 unblock request manually. Factors that influence their decision include:

A clear intended use: internal mail server, transactional app, or relay for clients.
Reverse DNS (PTR record) configuration that matches your sending hostname.
Your AWS account history: account age, verified payment method, and region used.
Estimated email volume and a mitigation plan in case of abuse.

What you'll need to provide

Instance ID and AWS region in use

Elastic IP (if already allocated)

Intended use for the mail server / SMTP relay

Domain for the PTR record configuration

port25-request.txt

# Example excerpt from a request we drafted

Instance: i-0abcxxxxxxxx (ap-southeast-3)

Purpose: internal transactional mail relay

PTR record: mail.example.co.id ✓

Request submitted via Support Center

Important note

Opening port 25 doesn't automatically guarantee inbox placement. We still recommend proper SPF, DKIM, and DMARC configuration so your sending reputation holds up regardless of the sending path used.

Process

Four steps to open port 25

Consult on Your EC2 Setup

We check the instance, region, and your mail server's intended use.

Prepare PTR & Justification

We guide the reverse DNS configuration and draft the usage reasoning.

Submit to AWS Support

The port 25 unblock request is submitted officially from your own AWS account.

Port Opened

We track the request status until outbound port 25 is active on your instance.