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· 7 min read

Free email API service (send and receive)

A free email API service that also receives — create an inbox, send, read replies and OTP codes over HTTP, no credit card. With the honest free-tier limits.

Search “free email API service” and you’ll find a dozen ways to send mail for free — and almost none that let you receive it. That’s the gap: a free email API service that also gives you a real inbox, so your code can read replies, pull verification codes, and hold two-way conversations. Here’s how that works, and the honest limits.

What you get on the free tier

No credit card. An API token. And a real, full-duplex email API:

  • Send from a mailbox’s own address.
  • Receive — every mailbox has a real receiving address.
  • Read messages as JSON, with extracted codes (OTPs) and links.
  • Test inboxes — disposable, unfiltered addresses for CI.

That’s more than most paid send-only tiers offer, because receiving is the part they skip.

Send and receive (code)

# create a mailbox
curl -X POST https://login.ollastack.com/api/mailboxes \
  -H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
  -d '{"name":"free","mode":"agent","handle":"hello"}'

# send from it
curl -X POST https://login.ollastack.com/api/mailboxes/mbx_.../send \
  -H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
  -d '{"to":"user@example.com","subject":"Hi","text":"Hello from a free email API"}'

# receive the reply
curl "https://login.ollastack.com/api/mailboxes/mbx_.../wait?timeout=60" \
  -H "Authorization: Bearer $TOKEN"

The honest free-tier limits

Be clear-eyed: the free send quota is modest and monthly — sized for AI agents, app inbound, and CI testing, not for sending tens of thousands of marketing emails. If you need high-volume one-way blasts, use a dedicated transactional provider (Resend, SendGrid, Mailgun) for the sending and this for the receiving and testing. We’d rather tell you that than have the free tier bounce on you.

vs other “free email API” tiers

Other free tiers give you more send volume but no receiving — so they can’t read a reply or an OTP. This one trades raw send volume for being full-duplex and free. Pick on what you need: volume → a sender; send + receive + test → this.

Where it fits

This is the free on-ramp to the email API. See the sibling free API to send email and inbound email API guides for the send and receive halves in depth.

Start free — send, receive, and test, no credit card.

Frequently asked questions

Is there a genuinely free email API service?

Yes. Ollastack's free tier gives you a real email API — create mailboxes, send, receive, and read messages over HTTP, plus disposable test inboxes — with no credit card. It's metered with a modest monthly send quota.

Does the free tier let me receive email, not just send?

Yes, and that's the point. Each mailbox has a real receiving address, so the free tier covers receiving replies, reading OTP codes and links, and replying in-thread — capabilities most free email APIs don't offer at all.

What are the free-tier limits?

Sending is capped at a modest monthly quota (suitable for agents, app inbound, and testing — not high-volume marketing blasts). Receiving and test inboxes are included. For high-volume one-way sending, pair a dedicated transactional provider.

Do I need a credit card to start?

No. You can create an account, get an API token, and start sending and receiving without a card.

Last updated June 21, 2026. Spotted something out of date? Email hello@ollastack.com.