The Smart API for cold email.
Unlimited mailboxes, sequences, sending windows, daily caps and bounce suppression behind one API. Email steps run in the same campaigns as LinkedIn steps, and every send, reply and bounce comes back as a webhook.
Beta: cold email is not fully available yet. We open it workspace by workspace while we finish it.
Unlimited
Mailboxes
Google, Microsoft and IMAP. You pay for the sends, not the inboxes.
1 POST
Sets up the whole sequence
Email and LinkedIn steps in the same sequence, with branches.
Auto
Bounce suppression
Hard bounces and spam complaints mark the address unusable; the lead stops at its next email step.
$59/mo
50,000 sends included
Every email sent counts, your own warmup included. Buckets up to 5M sends, then a Scale contract.
Mailboxes, sequences and replies as API resources
Connect Google, Microsoft or IMAP mailboxes from the dashboard. Everything after that is API: list them with their daily limits and usage, pause or resume one, read its stats, and point a campaign’s email steps at a pool of them with emailAccountIds. Each lead keeps the same mailbox for the whole thread.
Full schemas and a live playground at developer.swarmhit.com.
The email channel, in four calls
api/v1GET /email-accounts · mailboxes, limits, usage
POST /campaigns · email steps, mailbox pool
POST /campaigns/{id}/leads · add the audience
GET /email-accounts/{id}/stats · sent, replies, bounces
Every email step, sequenced
Each one runs inside the Smart API’s sequencer, next to your LinkedIn steps, paced by mailbox and by sending window.
Email steps
subject and body with lead variables and fallbacks
Same-thread follow-ups
threaded under the first email
Mailbox pools
one mailbox per lead for the whole thread
Daily caps
per-mailbox limits and today's usage
Sending windows
timezone, hours and days per campaign
Email and LinkedIn branches
route each lead to the channel it has
Bounce suppression
dead addresses skipped automatically
Replies in one inbox
read and answer them over the API
A cold email API with the sequencer built in
Sending APIs hand you one message at a time and leave the campaign to you: the queue, the delays, the daily limits, the follow-ups and the reply detection. On Swarmhit, an email is a step in a sequence. It sends from the campaign’s mailbox pool inside the sending window, follows up in the same thread, and stops the moment the lead replies.
Cold email and LinkedIn in the same campaign
One campaign takes a LinkedIn sender pool and a mailbox pool. Visit the profile, send the invitation, and when it is not accepted, branch on whether the lead has an email address and follow up there. Replies from both channels land in the same inbox and the same webhook stream, so your product sees one activity timeline per lead.
Deliverability you can read in the API
Every mailbox exposes its daily caps, today’s usage, its pause state and lifetime counters for sends, bounces and complaints. The stats endpoint adds replies and period-over-period deltas. A hard bounce or a spam complaint marks the address unusable, so no campaign emails it again.
Mailboxes you own, connected in minutes
Connect Google, Microsoft or IMAP mailboxes from the dashboard, as many as your volume needs. Their credentials are never returned by the API.
Pricing
Unlimited mailboxes. Pay for monthly sends.
50k
$59
125k
+$35
250k
+$45
500k
+$60
1M
+$120
2M
+$220
5M
+$560
5M+
Talk
We’re in beta, pricing might be subject to change. Every email sent through Swarmhit counts, warmup you send included. LinkedIn senders are added on the same invoice.
One infrastructure. Every outreach channel.
FAQ
The cold email API, answered.
- Sequencer built in
- Bounce and complaint suppression
- REST API and webhooks
Cold email, the Smart API way.
Plug your product into it.
Get an API key, connect a mailbox from the dashboard, and set up your first email sequence in one POST.