head to head
Amazon SES vs Postmark
Lowest cost per email versus highest deliverability per email.
What matters for teams building autonomous agents
An agent stack treats email as a two-way primitive. Inbound has to arrive as structured JSON a tool call can consume, sends have to be safe to retry when a model loop repeats itself, and every action needs an audit trail. A provider without inbound parsing only solves half the problem.
| Priority | Amazon SES | Postmark |
|---|---|---|
| Inbound parsing | Yes | Yes |
| Idempotency keys | No | No |
| Webhooks | No | Yes |
| Operating since | 2011 | 2010 |
| Event stream | Yes | Yes |
| Best published rate per 1,000 | $0.10 | $1.50 |
| Batch sending | Yes | Yes |
| SDKs | node, python, go, ruby, php, java, rust, dotnet | node, python, go, ruby, php, java, elixir, rust, dotnet |
| Multi-tenant | No | Yes |
For an agent that reads and writes email running inbound parsing into tool calls and model-generated sends that must not duplicate, Postmark takes webhook coverage, operating track record, SDK breadth, and multi-tenant support, while Amazon SES takes best published rate per 1,000. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Amazon SES | Postmark |
|---|---|---|
| Webhooks | No | Yes |
| SDKs | node, python, go, ruby, php, java, rust, dotnet | node, python, go, ruby, php, java, elixir, rust, dotnet |
| Multi-tenant | No | Yes |
| Tagline | Cheapest at scale, most setup work. | Transactional-only, fast and well-delivered. |
| Free tier | Up to $200 in AWS Free Tier credits for new accounts | 100/mo developer plan |
| Starts at | $0.10 per 1,000 emails | $15/mo for 10,000 emails |
| Pricing model | pay-as-you-go | tiered |
| API | Yes | Yes |
| SMTP | Yes | Yes |
| Templates | basic | rich |
| React Email | No | No |
| Inbound | Yes | Yes |
| Idempotency | No | No |
| Dedicated IP | Yes | Yes |
| Deliverability | Inherits AWS IP reputation. Generally good once warmed and configured, but the sender does the warming and complaint handling. | Strong transactional reputation with separate streams for transactional and broadcast traffic, which helps protect sender reputation. |
| DX score | 4/10 | 9/10 |
| Best for | High-volume senders with AWS infrastructure, cost-optimized workloads, and teams comfortable wiring SNS/Lambda/EventBridge for events. | Teams where password resets, receipts, and magic links absolutely cannot miss the inbox. |
Amazon SES
pros
- ›Cheapest cost per email, by a large margin at scale
- ›Built for billions: handles the largest sender workloads in the world
- ›Multi-region (us-east-1, us-west-2, eu-west-1, ap-south-1, and more) with regional reputation pools
- ›Native integration with Lambda, SNS, SQS, EventBridge, and CloudWatch
- ›Dedicated IPs and managed dedicated IP pools
- ›VPC endpoints for sending from private networks
- ›Inbound receiving with S3 and Lambda for fully serverless email pipelines
- ›SDKs in every language AWS supports, from Rust to .NET
- ›IAM-based authentication; no separate API keys to manage
cons
- ›Sandbox mode requires manual approval before sending to non-verified recipients
- ›No native webhooks; events route through SNS and you write your own glue
- ›No dashboard for message-level debugging
- ›Bounce and complaint handling is the sender's responsibility
- ›Templates are minimal
- ›Operational overhead is real if you are not already on AWS
Postmark
pros
- ›Transactional-only routing and strong operational history
- ›Streams cleanly separate transactional and broadcast
- ›Free DMARC monitoring product (dmarc.postmarkapp.com)
- ›Retains full message content and metadata for 45 days for debugging
cons
- ›No idempotency keys
- ›Pricing per email is higher than SES, Mailgun, or SMTP2GO
- ›No drag-and-drop template builder
- ›Marketing automation is intentionally absent