The short version
| Stamp0 | Resend | |
|---|---|---|
| API | Resend-compatible REST API | Resend REST API |
| Who sends the mail | Amazon SES in your AWS account, or Cloudflare Email Service in your Cloudflare account (beta, transactional only) | Resend’s infrastructure |
| Sending cost | $0.10 per 1,000 (AWS, à la carte) | Up to $0.90 per 1,000 |
| Software price | Flat per workspace, from $0 | Tiered by monthly volume |
| Email bodies stored | Your S3 bucket | Resend |
| Inbound email | SES receiving, inboxes and threads | Inbound and Inboxes |
| Marketing email | Campaigns, sequences, lists, segments, forms; priced on contacts | Broadcasts, automations, topics, segments |
| Agent tooling | Remote MCP with high-level tools, CLI, skills | MCP server |
| AWS credits | Apply to sending | Do not apply |
Cost at every volume
Resend prices transactional email by monthly volume: a free plan for 3,000 emails, Pro from $20 for 50,000, and Scale plans up to $1,150 for 2.5 million, with overage between $0.46 and $0.90 per 1,000. Stamp0 adds a flat plan price to what AWS charges you for SES, $0.10 per 1,000 emails.
| Emails a month | Resend | Stamp0 + SES | You save |
|---|---|---|---|
| 3,000 | $0 (Free) | $0.30 (Free) | — |
| 50,000 | $20 (Pro) | $5 (Free) | $15 |
| 100,000 | $35 (Pro) | $25 (Pro) | $10 |
| 250,000 | $170 (Pro) | $40 (Pro) | $130 |
| 500,000 | $350 (Scale) | $65 (Pro) | $285 |
| 1,000,000 | $650 (Scale) | $115 (Pro) | $535 |
| 2,500,000 | $1,150 (Scale) | $265 (Pro) | $885 |
At the bottom of the range Resend’s free plan wins, and Stamp0 matches it: the Stamp0 free plan covers 50,000 emails a month, so you pay only AWS’s few dollars. From there the gap grows with volume, because Stamp0 never charges per email. Prices are list prices from Resend and AWS, checked 2026-10-19.
Migrating takes two settings
The Resend SDKs read their base URL from the RESEND_BASE_URL environment variable or a baseUrl option. Point it at Stamp0 and swap the key:
RESEND_API_KEY=s0_… # a Stamp0 API key
RESEND_BASE_URL=https://api.stamp0.com- Connect your AWS account with the one-click CloudFormation stack.
- Add your sending domain. Stamp0 writes the DKIM and MAIL FROM records on Route 53, or lists them for any other DNS provider.
- Create an API key and set the two variables above.
- Recreate webhooks with the same URLs; the event payloads match.
See the quickstart for the full walkthrough.
Data ownership
With Resend, message content lives on Resend’s side. With Stamp0, HTML, text, attachments and raw inbound mail are written to an S3 bucket in your account; Stamp0 stores metadata such as recipients, subject, status and events (plus contacts and templates if you use marketing email). Sending reputation, suppression lists and SES quotas belong to your AWS account, so they stay with you if you ever stop using Stamp0.
Agents and MCP
Stamp0’s MCP server is designed around jobs rather than endpoints: set up a domain end to end, diagnose a bounce spike, draft a production-access request, triage an inbox. Agent keys can be bound to a single inbox, so an assistant can answer support mail without being able to send from your billing address. Read the MCP guide.
What you take on
Sending from your own AWS account is not free of trade-offs:
- You need an AWS account, and new SES accounts start in the sandbox until AWS grants production access. Our sandbox guide covers it.
- AWS reviews your bounce and complaint rates. Stamp0 tracks both against the SES thresholds so you see trouble first.
- Two bills instead of one: AWS for sending, Stamp0 for the software. Together they are usually far smaller than one Resend bill.