Email inbox API: a real inbox over HTTP
Give your app or agent a real inbox over HTTP — create it, send, receive, and read messages as JSON. How it differs from a send-only email API.
A sending API can push a message out, but it can’t hold a conversation. An email inbox API can: it gives your code a real, addressable inbox that sends and receives, so your app or agent can read replies, pull verification codes, and act on inbound mail — all over HTTP, no mail server.
What an email inbox API is
It’s a real inbox behind an API. You create one, and it gives you an address that can receive mail and an id you use to send, read, and reply. Messages come back as JSON. That’s the difference from a sending-only API: the inbox is a two-way object your code owns.
Create and read an inbox
# create an inbox
curl -X POST https://login.ollastack.com/api/mailboxes \
-H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
-d '{"name":"app inbox","mode":"agent","handle":"team"}'
# → { "id":"mbx_…", "address":"team@agent.ollastack.com" }
# list what it has received
curl "https://login.ollastack.com/api/mailboxes/mbx_.../messages" \
-H "Authorization: Bearer $TOKEN"
# or block until the next message arrives
curl "https://login.ollastack.com/api/mailboxes/mbx_.../wait?timeout=60" \
-H "Authorization: Bearer $TOKEN"
Each message returns the subject, bodies, and extracted codes/links — read fields, don’t scrape HTML. To send from the same inbox, POST /api/mailboxes/{id}/send; to reply in-thread, POST /api/mailboxes/{id}/messages/{id}/reply.
Inbox vs send-only API
A send-only API answers “did it go out?” An inbox API answers “what came back?” — replies, codes, inbound support mail. If your product only blasts notifications, a sender is enough; if it needs to read mail (agents, 2FA flows, support, testing), you need an inbox.
Persistent vs disposable
- Persistent (agent) inbox — a chosen handle that lasts and is spam-filtered. For an identity your app or agent keeps using. See agent email identity.
- Disposable (test) inbox — a throwaway address, never spam-filtered, for CI and one-off verifications. See email testing API for CI.
Same API, two guarantees — pick per use.
Where it fits
The inbox API is the receive-and-converse layer; sending lives on the same token. See the email API overview, and the sibling inbound email API guide for the webhook/parsing detail.
Create an inbox — send, receive, and read over HTTP, free to start.
Frequently asked questions
What is an email inbox API?
An email inbox API gives your code a real, addressable inbox it operates over HTTP — create the inbox, send from it, receive into it, and read messages (with extracted codes and links) as JSON. Unlike a send-only email API, it holds two-way conversations.
How is an inbox API different from a sending API?
A sending API (SendGrid, Resend, Mailgun) only pushes mail out. An inbox API also receives: it has a real address that accepts incoming mail and exposes it to your app, so you can read replies, OTP codes, and inbound messages — not just send.
What's the difference between a persistent and a disposable inbox?
A persistent (agent) inbox is a chosen handle that lasts and is spam-filtered — for an identity your app or agent keeps using. A disposable (test) inbox is a throwaway address that's never spam-filtered — ideal for CI and one-off verifications.
Is there a free email inbox API?
Yes. Ollastack's free tier includes inboxes you can send from, receive into, and read over HTTP, with no credit card.
Last updated June 21, 2026. Spotted something out of date? Email hello@ollastack.com.