What’s the difference between Postfix, Exim, and PowerMTA?

These three MTAs represent different approaches to mail server software.

Postfix:

Open source, widely deployed

Designed for security and reliability

Modular architecture, relatively easy to configure

Excellent documentation and community

Good choice for most self-hosted scenarios

Default on many Linux distributions

Exim:

Open source, highly flexible

Powerful configuration language for complex routing

Steeper learning curve than Postfix

Popular in hosting environments (cPanel default)

Good when you need sophisticated routing rules

Strong filtering and processing capabilities

PowerMTA:

Commercial software (licensing required)

Built for high-volume deliverability

Advanced features: automatic IP warmup, bounce categorization, detailed analytics

Virtual MTA support for IP management

Used by ESPs and large senders

Significant cost but purpose-built for email delivery at scale

Choosing between them:

Limited budget, moderate needs: Postfix

Complex routing, hosting environment: Exim

High volume, deliverability focus, budget available: PowerMTA

Postfix and Exim are free; PowerMTA costs thousands annually but provides capabilities that would require significant custom development otherwise.