Send email with curl, free (and read the reply)
Send email with one curl command, free — no SMTP. Plus the honest truth about 'no API key' senders and how to receive the reply from the shell.
You want to send an email from a script or the terminal without standing up SMTP. curl can do it in one line — and, unlike most “send email” snippets, you can read the reply with the same tool. Here’s the honest, working way.
The one-liner
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":"Sent from curl."}'
# → { "id": "msg_…", "status": "sent" }
One HTTPS POST. No SMTP host, no port 587, no app password. Create the mailbox once (POST /api/mailboxes) and reuse its id.
About “no API key”
Searches for “send email with curl no api key” want zero friction — but be honest about the tradeoff. Truly keyless public senders are unauthenticated relays: heavily rate-limited, spam-filtered to oblivion, and a magnet for abuse, so they’re useless for anything you actually rely on. A free API token is the honest minimum — it costs nothing, it authenticates you, and it keeps the endpoint from becoming an open relay that spammers ride. Free, yes; keyless, no — and you don’t want keyless.
No SMTP, no server
There’s nothing to run. curl talks straight to the API over HTTPS; the platform handles delivery from an authenticated domain (SPF/DKIM/DMARC already passing). To send from your own domain, add a custom sender — see DKIM, SPF & DMARC.
Receive the reply with curl too
The same token long-polls for the response — send and receive, both from the shell:
curl "https://login.ollastack.com/api/mailboxes/mbx_.../wait?timeout=60" \
-H "Authorization: Bearer $TOKEN"
See the email API overview and free API to send email.
Get a free token — send and receive from curl, no card.
Frequently asked questions
How do I send email with curl for free?
POST to the send endpoint with an Authorization header and a JSON body: curl -X POST https://login.ollastack.com/api/mailboxes/{id}/send -H 'Authorization: Bearer TOKEN' -H 'Content-Type: application/json' -d '{"to":"...","subject":"...","text":"..."}'. The free tier needs no credit card.
Can I send email with curl with no API key at all?
Truly keyless public senders exist but are unauthenticated relays — rate-limited, spam-prone, and unreliable for anything real. A free API token is the honest minimum: it's free, it authenticates you, and it stops your endpoint becoming an open relay.
Do I need SMTP for curl email?
No. You make one HTTPS POST. There's no SMTP host, port, or password — curl talks to the API directly.
Can curl also receive the reply?
Yes. curl the wait endpoint with the same token to long-poll for the next inbound message — send and receive, both from the command line.
Last updated June 21, 2026. Spotted something out of date? Email hello@ollastack.com.