Building Simple Email Service on EC2
Email is a common requirement for applications, whether it is used for notifications, alerts, verification emails or password resets. One simple way to understand how email delivery works is to host an SMTP server on an Amazon EC2 instance.
Architecture
A basic setup looks like:
Application -> AWS EC2 (SMTP Server) -> Recipient Mail Server
The EC2 instance can run an SMTP server such as Postfix. The application connects to the SMTP service and submits emails for delivery.
Key Components
The setup typically includes:
- Amazon EC2 – hosts the SMTP server.
- Postfix – handles email transmission.
- DNS – provides the mail server hostname and email records.
- TLS – protects SMTP communication.
- SPF, DKIM, and DMARC – improve email authentication and deliverability.
For example, an application can connect to an SMTP submission endpoint on port 587 and authenticate before sending an email.
Security Considerations
An SMTP server should never be configured as an open relay. Authentication, TLS, firewall rules, rate limiting and monitoring are essential.
DNS records such as SPF, DKIM and DMARC should also be configured to help receiving mail providers verify that messages are legitimate.
AWS also places restrictions around outbound SMTP traffic from EC2, so the current AWS requirements should be checked before deploying a direct-to-internet mail server.
EC2 or Amazon SES?
Running SMTP on EC2 provides more control but also requires you to manage the server, security, reputation, scaling and deliverability.
For production applications, Amazon SES is often a simpler option because AWS manages much of the underlying email-delivery infrastructure.
Verdict
Hosting a simple SMTP service on Amazon EC2 is a useful way to learn how application-level email delivery works. For production workloads, combining an application running on EC2 with Amazon SES can provide a more scalable and operationally efficient architecture.
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