Is Postmark or AWS SES better for transactional email?

Postmark is better for deliverability and simplicity. AWS SES is better for high-volume senders who can invest in configuration and monitoring. Postmark has industry-leading inbox placement for transactional mail.

How much does Postmark cost compared to AWS SES?

Postmark costs $1.25/1,000 emails. AWS SES costs $0.10/1,000 emails. At 100K emails/month, that's $125 vs $10. The gap widens at scale but Postmark includes features SES charges extra for.

Does AWS SES have good deliverability?

AWS SES can achieve excellent deliverability but it requires proper warmup, monitoring, bounce handling, and reputation management. Out of the box, SES doesn't optimize for deliverability—you must configure it correctly.

Can I use AWS SES for marketing email?

Yes, but SES doesn't enforce content policies like Postmark. This means shared IP reputation can be lower. For marketing email, dedicated IPs and proper list hygiene are essential on SES.

Does Postmark work with AWS?

Yes. Postmark is a separate service but integrates with any stack. You can run your application on AWS and use Postmark's API or SMTP for transactional email without conflict.

Postmark vs AWS SES: Simplicity vs Scale in Transactional Email

The Core Tradeoff

Postmark and AWS SES represent opposite philosophies in transactional email:

Postmark: Opinionated, transactional-only, premium deliverability, higher price AWS SES: Flexible, DIY configuration, low price, deliverability is your responsibility

There's no universally "better" option. The right choice depends on your volume, engineering resources, and how critical email deliverability is to your business.

Pricing Comparison

Volume/Month	Postmark	AWS SES	Difference
10,000	$15	$1	15x
50,000	$62.50	$5	12.5x
100,000	$125	$10	12.5x
500,000	$625	$50	12.5x
1,000,000	$1,200	$100	12x

AWS SES costs roughly 10% of Postmark at any volume. But this comparison ignores hidden costs.

What Postmark Includes

Dedicated IP pools optimized for transactional mail
Real-time bounce and complaint handling
Built-in analytics and deliverability reporting
Templates and message streams
45-day message retention with full search
Human support from deliverability experts

What AWS SES Requires You to Build

Bounce and complaint handling via SNS
Monitoring and alerting infrastructure
IP warmup management (if using dedicated IPs)
Reputation dashboard (via CloudWatch)
Log aggregation and search
Deliverability expertise on your team

Practitioner note: I've seen companies "save money" by switching from Postmark to SES, then spend 40 engineering hours configuring bounce handling, monitoring, and fixing deliverability issues. At $150/hour, that's $6,000 before you've sent a single email.

Deliverability Comparison

Postmark's Approach

Postmark is transactional-only. They reject accounts that try to send marketing email. This policy keeps their shared IP pools exceptionally clean.

Their infrastructure is optimized for:

Password resets
Order confirmations
Shipping notifications
Account alerts

Because every sender on Postmark sends similar content, IP reputation stays high. Transactional email from Postmark typically lands in the primary inbox, not Promotions.

AWS SES's Approach

SES lets you send anything—transactional, marketing, cold outreach. This flexibility is powerful but dangerous. Shared IP reputation varies based on what other senders do.

To achieve Postmark-level deliverability on SES:

Use dedicated IPs ($24.95/month per IP)
Warm up properly over 2-4 weeks
Implement proper bounce/complaint handling
Monitor reputation via SES dashboard
Maintain list hygiene and suppress bad addresses

Practitioner note: AWS SES deliverability out of the box is mediocre. With proper configuration, it can match any provider. The question is whether you have the expertise and time to get there.

Feature Comparison

Feature	Postmark	AWS SES
SMTP	Yes	Yes
REST API	Yes	Yes
Webhooks	Yes	Via SNS
Templates	Yes (with Mustachio)	Yes
Dedicated IPs	Included (managed)	$24.95/IP/month
Bounce handling	Automatic	DIY via SNS
Complaint handling	Automatic	DIY via SNS
Analytics	Built-in dashboard	CloudWatch + manual
Support	Email + chat (humans)	Paid support plans
SLA	99.99%	99.9%

When to Choose Postmark

Choose Postmark if:

Transactional email is business-critical (password resets, invoices, alerts)
You want excellent deliverability without configuration
Your team doesn't have dedicated email infrastructure expertise
You value support from actual deliverability experts
Volume is under 500K/month
You need to separate transactional from marketing cleanly

Postmark's "message streams" feature lets you isolate transactional and broadcast email, protecting transactional deliverability from marketing reputation issues.

When to Choose AWS SES

Choose AWS SES if:

You're already heavily invested in AWS
Volume exceeds 500K-1M emails/month
You have engineering resources to build monitoring and handling
Cost is the primary decision factor
You need to send mixed content (transactional + marketing)
You want maximum control over infrastructure

At 1M+ emails/month, the cost difference is substantial: $100/month vs $1,200/month. That savings can fund the engineering time to manage SES properly.

Migration Considerations

Postmark to SES

If migrating from Postmark to SES to save money:

Set up SNS topics for bounces and complaints
Build handlers to process these notifications
Create suppression list infrastructure
Warm dedicated IPs over 2-4 weeks
Monitor deliverability closely during transition
Keep Postmark active until SES is fully warmed

Don't cut over cold. Run parallel for at least a month.

SES to Postmark

If migrating from SES to Postmark for better deliverability:

Sign up and verify your domain (DKIM, Return-Path)
Start sending transactional email immediately—no warmup needed on Postmark's shared pools
Use message streams to separate transactional from any broadcast
Migrate templates to Postmark's format
Update webhook endpoints from SNS to Postmark's direct webhooks

Postmark migration is faster because their shared infrastructure is pre-warmed.

The Hybrid Approach

Many companies use both:

Postmark for critical transactional email (password resets, 2FA, payment receipts)
AWS SES for high-volume notifications (activity digests, marketing)

This protects mission-critical email deliverability while keeping costs reasonable for bulk sends.

Practitioner note: I recommend this hybrid approach for most SaaS companies. Your password reset emails must land immediately—that's worth Postmark's premium. Your weekly digest can tolerate slightly lower deliverability at 10% of the cost.

If you're unsure which architecture fits your sending patterns, schedule a consultation to map out the right infrastructure for your volume and use case.

Sources

v1.0 · March 2026