The short answer
- Pick the provider that keeps verification links, password resets, receipts and product notifications working at your busiest expected volume. Month-level price comparisons do not establish burst capacity or inbox receipt. recipe
- Under 3,000 a month and 100 a day: Resend's free plan, which doesn't expire. resend.com
- SES can suit a team optimizing send cost while owning account readiness and email operations. Requesting production access is a prerequisite to check, not proof that a new account can already serve customers. docs.aws.amazon.com
- Postmark exposes Transactional and Broadcast message streams. Compare that separation with your actual traffic, alongside templates, events and inbound mail needs. postmarkapp.com
The economics
The tables use dated catalog evidence for published plans and overages. They compare sending costs at the stated volume, not a fresh quote or the total cost of migration and email operations.
Monthly cost by volume
| Emails a month | 3,000 | 10,000 | 50,000 | 100,000 | 300,000 |
|---|---|---|---|---|---|
| Resend | $0Free, 100/day cap | $20Pro | $20Pro | $35Pro 100k | $215Pro 100k, plus overage |
| SendGrid (Twilio) | $19.95Essentials | $19.95Essentials | $19.95Essentials | $34.95Essentials 100k | $214.95Essentials 100k, plus overage |
| Postmark | $15Basic | $15Basic | $66Platform, plus overage | $126Platform, plus overage | $366Platform, plus overage |
| Mailgun | $0Free, 100/day cap | $15Basic | $35Foundation | $90Scale | $310Scale, plus overage |
| Amazon SESattachments extra | $0.30Pay as you go | $1Pay as you go | $5Pay as you go | $10Pay as you go | $30Pay as you go |
- Postmark's page shows only its 10,000-email step, so above that the catalog prices extra emails at the published overage; check its slider for volume tiers. postmarkapp.com
- Check the busiest day and recipient count as well as the monthly total. Resend counts individual recipients and inbound messages against its email quota, so a single-recipient send model may understate your usage. resend.com
What the free tiers really are
Pick by situation
- Before launch or a side project: Resend Free, 3,000 emails/mo, 100 emails/day, 3 domains, 30-day data retention; no pay-as-you-go on Free. resend.com
- Launched, under 50,000 a month: a flat plan is simplest. Resend Pro at $20/mo and SendGrid Essentials at $19.95/mo both include 50,000. resend.com
- Lower send cost with an operations owner: consider SES after checking production access and arranging delivery, bounce and complaint notifications. Its billing figure leaves out the application work to act on those events. docs.aws.amazon.com
- Distinct transactional and broadcast flows: evaluate Postmark message streams and their unsubscribe behavior. Separate the product event that triggers a message from the provider stream used to deliver it. postmarkapp.com
- The current route already works: keep it when templates, deliverability monitoring and message history matter more than the modeled subscription reduction. Choose a replacement only after mapping the narrower job in the recipe. recipe
Compare before choosing
Considering a specific destination? Read its checked comparison before deciding what to move.
- Resend vs Amazon SES Checked migration details, public switching accounts.
- Resend vs useSend Checked migration details, public switching accounts.
A real workflow: ask your agent
- Ask your agent to price the job at your real volume. choose_stack returns, per provider, the cheapest published tier that covers your number, with a link to the pricing page, and asks for any number it doesn't have. stackcut.io
- Make the message inventory: identify each event, its recipients, sender, template and required links. Map the destination API and message fields before changing production traffic. resend.com
- Set up the sender identity: verify a domain or sending subdomain you control. Keep reset links and other essential transactional mail separate from newsletter tracking decisions. resend.com
choose_stack({"project": "B2B SaaS app", "needs": [
{"job": "email_transactional",
"volume": {"amount": 40000, "unit": "emails_per_month"}}]})- A plan counts as a fit only when its published limit covers your number; trials and one-time credits never count as free. stackcut.io
- Make retries safe: store the business event and use a stable request identity. Where supported, send with an idempotency key; do not turn an uncertain network response into a second customer receipt. resend.com
- Check the complete outcome: exercise verification and reset links, inspect delivery/bounce events and confirm that your application updates its own message state. An accepted API send is only one step. resend.com
- Preserve recipient hygiene: carry forward suppressions and check how the destination applies them. SES account-level suppressions need deliberate configuration and handling. docs.aws.amazon.com
Fit
A good fit if
- You send transactional email from your app through an API or SMTP. recipe
- You can measure monthly demand, busy-day demand and recipient counts rather than relying on a smooth monthly average. resend.com
- Someone will own sender configuration and the delivery, bounce and complaint event workflow after launch. docs.aws.amazon.com
Look elsewhere if
- You send newsletters to a list: that's email marketing, priced by subscribers. See the newsletter use case. recipe
- Inbound email, templates or broadcasts are core to your product: check each plan's extras, not only the send price. recipe
- You want to rewrite sending infrastructure purely because AI makes the first implementation quick. The recipe cost model includes setup and upkeep; a custom adapter does not remove managed-delivery and operational requirements. recipe
Questions
Is Resend's free plan enough for a startup?
Until you pass 3,000 emails a month or 100 in a day. Free has no pay-as-you-go, so plan the upgrade before launch day. resend.com
Which free plans are really free?
Resend's is an ongoing free plan: 3,000 emails/mo, 100 emails/day, 3 domains, 30-day data retention; no pay-as-you-go on Free. resend.com
Mailgun's free plan allows 100 emails a day. mailgun.com
Postmark's Developer plan is 100 emails a month. postmarkapp.com
SendGrid's is a 60-day trial. twilio.com
Amazon SES gives new AWS accounts credits instead of a free allowance. aws.amazon.com
What does SES cost at 300,000 emails a month?
$30/mo, before attachments, at the a la carte rate of $0.10 per 1,000. aws.amazon.com
What should I check before switching providers?
Verify the destination domain, map the message fields and test the actual verification, reset and receipt flows. Keep the prior route available until destination delivery and event handling are working. Do not route the same business event through both providers without duplicate protection. resend.com
Should I build an email service or a small application layer?
Building the event-to-message workflow, queue or reporting interface may improve fit without replacing a delivery provider. SES offers delivery, bounce and complaint notifications for such a layer. Price the work to process them and to recover failures before declaring the custom route cheaper. docs.aws.amazon.com
How do I handle a launch-day sending spike?
Check daily quota, monthly quota and sending rate independently. Resend’s free daily limit resets on a UTC calendar day, and its account limits count each recipient. Schedule, queue or upgrade based on actual peak demand rather than spreading a forecast evenly across the month. resend.com
What does a delivery event prove?
It is stronger evidence than only recording a successful send request, but your acceptance check should also cover the real user flow. Resend provides delivery and bounce events through webhooks; store and handle those events so the application can diagnose missing account emails. resend.com
How do I preserve suppressions during a move?
Retain the reason a recipient should not receive more mail and reproduce that restriction at the destination. Resend’s managed suppression lists support dashboard/API management and bulk imports; review that behavior before resuming sends. resend.com
Next steps
- Resend and SendGrid alternatives in 2026: what to use instead, and what it really costs
- Database and auth for an MVP: what it costs from 1,000 to 250,000 users
- A newsletter for your first 10,000 subscribers: what it costs at each size
- Vercel alternatives in 2026: what to use instead, and what it really costs
- Recipe: Transactional email API
- Recipe: Transactional email API
Check your own stack
Get your free stack audit
Stackcut finds every software subscription in your inbox and shows what to cancel, what to pay per use, and what AI can replace, with a spec and a cost for each. Your stack audit is free and takes about 2 minutes.
Or ask your agent
Connect the Stackcut MCP server (https://stackcut.io/mcp, no API key) and ask: “We send about 40,000 transactional emails a month. What's the cheapest provider that fits?”
choose_stack({"project": "B2B SaaS app", "needs": [
{"job": "email_transactional",
"volume": {"amount": 40000, "unit": "emails_per_month"}}]})