EmailHorizon is in a private beta for agencies and outbound teams. Request access
EmailHorizon
Request access

EmailHorizon cold email

Cold email that stops when they reply.

Send from your own mailboxes. Write the sequence once, and EmailHorizon follows up on schedule until a lead replies, bounces or unsubscribes.

Request access

Gmail, Google Workspace and any SMTP and IMAP account

Built into every account

  • SPF, DKIM and DMARC checks
  • Private warmup pool
  • Spam rescue
  • One-click unsubscribe
  • A/B auto-winner
  • Lead time zones
  • Conditional steps
  • Master inbox
  • Email verification
  • Signed webhooks
  • MCP server
  • Unlimited workspaces

Every reply stops the sequence.

Play one week of a campaign. Then turn Stop on reply off and watch what happens without it.

Founders in fintech

3 steps, 2 days apart · 3 sending mailboxes

Stop on reply
Mon 09:00
MonTueWedThuFri

Priya Nair

Scheduled

Daniel Brooks

Scheduled

Lena Fischer

Scheduled

Arjun Mehta

Scheduled

Grace Kim

Scheduled

  1. Mon 09:00Campaign launched. Sending 09:00 to 17:00, Monday to Friday.
Fig. 1 One campaign over a working week. Example leads and times.

How it works

From mailbox to reply, in three steps.

  1. 01

    Connect your mailboxes

    Gmail and Google Workspace with an app password, or any SMTP and IMAP account. One at a time or a whole CSV file at once.

    Mailboxes

    3 connected

    Connect a mailbox

    Gmail or WorkspaceSMTP and IMAPBulk from a CSV

    SMTP and IMAP are both checked live before a mailbox is saved.

  2. 02

    Write the sequence once

    Steps, waits in minutes, hours or days, A/B variants, conditions, variables and spintax, all in one editor.

    Sequence

    Founders in fintech

    1. Step 1

      AQuick question

    2. Wait 2 days

      Step 2 · same thread, A/B by replies

      ARe: Quick questionWinner
      BRe: Quick question

    3. Wait 48 hours

      Step 3 · only if not opened

      AA different angle

    Step 1, variant A

    Subject Quick question

    {Hi|Hello} {{ first_name }},

    Saw {{ company }} is hiring for sales. We help teams like yours book meetings without adding headcount.

    Worth a short call next week?

    Spintax and variables are filled in for each lead.

  3. 03

    Answer every reply in one inbox

    Replies from every mailbox arrive live, spam folder included, and that lead gets no more follow-ups.

    Master inbox

    maya@, sam@, jo@

    • Tom Walker

      Automated9 min

      Out of office · to sam@

      I am away until Monday and will reply when I am back.

    • Mail delivery

      Bounced18 min

      Delivery failed · to jo@

      The address [email protected] could not be found.

    • Grace Kim

      Reply27 min

      Re: Following up · to sam@

      Thanks, we already work with someone for this.

    Example replies, arriving live as they do in the app.

Everything included

Built for how agencies actually send.

Twelve parts of one product, all in the app today.

Sequences

Multi-step campaigns that stop on reply.

  • Follow-ups in the same thread, waits in minutes, hours or days
  • Steps that only go out if the lead opened, clicked or replied, or did not
  • Variables, custom fields and spintax
A/B tests

Variants with a winner you can trust.

  • Variants on every step, subject and body
  • Winner by replies, opens or clicks
  • Picked only once a statistics test says the gap is real
Scheduling

Sending windows, limits and time zones.

  • Days, hours and time zone per campaign
  • Or each lead's own time zone
  • Limits per campaign, mailbox and receiving domain
Warmup

A private pool that builds reputation.

  • Google pairs with Google, Microsoft with Microsoft
  • Starts at 2 a day and adds 2 a day up to your limit
  • Replies at the rate you set and rescues mail from spam

Ramp, 2 more each day

Deliverability

Checks and guardrails on every domain.

  • MX, SPF, DKIM, DMARC and blocklist checks, daily
  • Health score per mailbox, pause at 5% bounces
  • Inbox placement tests on seed inboxes
  • MXMail servers foundPass
  • SPFSoft fail (~all)Pass
  • DKIMSelector googlePass
  • DMARCp=quarantinePass
Leads

Lists, tags, fields and blocklists.

  • CSV import with column mapping and duplicate rules
  • Lists, tags, custom fields and statuses
  • Blocklists for addresses and whole domains
Verification

Check addresses before you send.

  • Syntax, MX, disposable, role and free provider checks
  • Optional SMTP check that spots catch-all domains
  • One address or a whole list at once
Master inbox

Every reply in one place, live.

  • Replies from every mailbox, including spam
  • Reply, reply all, forward, compose, saved templates
  • Mark interested, snooze, or assign to a teammate

Quick question about your team

Sounds useful. Are you free Thursday for a call?

Priya Nair replied · follow-ups stopped

Analytics

Live numbers for every campaign.

  • Sent, opened, replied, bounced, unsubscribed, interested, clicked
  • Per workspace, campaign, step and mailbox, with charts
  • Scanners and bots filtered out of opens and clicks

Sent, opened and replied, per step

Workspaces

One per client, with roles.

  • Unlimited workspaces with separate data
  • Roles: Admin, Editor, Client and Reseller
  • Invitations and API keys per workspace
API and MCP

Everything in the app, from code.

  • REST API with an OpenAPI 3.1 description
  • 27 signed webhook events with logs and replay
  • MCP server for AI assistants, and the ehcli command line

Warmup

Private pool

Ramp of [email protected]

Day 9 of 15

Day 1, 2 emailsDay 15, limit of 30

score = (sent − saved from spam) ÷ sent × 100
455 sent, 2 saved from spam: 99.56

Warmup

Warmup that shows its work.

New mailboxes build a sending reputation in a private pool before your first campaign, and you can see exactly how.

  • Google pairs with Google, Microsoft with Microsoft
  • Starts at 2 emails a day and adds 2 a day up to your limit
  • Partners reply in the same thread, 10 to 90 minutes later
  • Warmup emails found in spam are moved back to the inbox
  • Scores over 3, 7, 10, 14 and 30 days, with alerts

Time zones

Sends while they are at work.

Turn on lead time zones and every lead gets your steps inside their own working hours. This one is live, from your clock.

Live 

 

  • Maya Chen

    San Francisco

    --:--

     

     

  • Daniel Brooks

    New York

    --:--

     

     

  • Lena Fischer

    Berlin

    --:--

     

     

  • Priya Nair

    Bengaluru

    --:--

     

     

  • Oliver Grant

    Sydney

    --:--

     

     

Fig. 2 Live from your clock. Real time zones, example leads, a 09:00 to 17:00 window on weekdays.

yourdomain.example

Example result

  • MX

    Where replies are delivered

    Google Workspace, 5 mail servers

    aspmx.l.google.com alt1.aspmx.l.google.com

  • SPF

    Which servers may send for you

    Soft fail for other servers (~all)

    v=spf1 include:_spf.google.com ~all

  • DKIM

    A signature on every email

    Key found on selector google

  • DMARC

    What receivers do with failures

    Policy p=quarantine

    v=DMARC1; p=quarantine; rua=mailto:[email protected]

Live DNS lookups for MX, SPF, DKIM on common selectors, and DMARC. We do not store the domains you check.

Deliverability

Check your domain right here.

The same MX, SPF, DKIM and DMARC checks the app runs every day. Type your domain and watch the answers arrive.

Domain checks
MX, SPF, DKIM, DMARC and blocklists for every sending domain, re-checked daily.
Pacing
Daily limits per mailbox and per receiving domain, with random gaps between sends.
Unsubscribe
One-click unsubscribe headers on every email, the format Gmail and Yahoo ask bulk senders for.
Bounces
A hard bounce stops that lead at once. A mailbox warns at 2% bounces and pauses at 5%.
Placement tests
Send to seed inboxes and see inbox or spam before you launch.

Workspaces

5 clients
Dental clinicsSaaS foundersReal estateRecruitingLogistics

SaaS founders

Own mailboxes, leads, campaigns and inbox

Nikhil Rao

[email protected]

Admin

Emma Davies

[email protected]

Editor

Lucas Martin

[email protected]

Client

Agencies

One workspace per client.

Each client gets separate mailboxes, leads, campaigns and inbox. Invite people as Admin, Editor, Client or Reseller, and give clients a login that only answers their replies.

Your mailboxes, your reputation.

Every email goes out from a mailbox you connected. There is no shared sending server for someone else to burn.

We review every account before it opens, because mailboxes that use warmup share one private pool.

Read the privacy policy

Developers

Run it from code, or from your AI assistant.

Everything in the app is in the API. With the MCP server, an assistant such as Claude can build, launch and pause campaigns and answer replies.

  • REST API with an OpenAPI 3.1 description
  • 27 signed webhook events, retried for about three days
  • MCP server, so AI assistants can act in your workspace
  • ehcli, a command line tool for scripts and CI

An assistant building a campaign

# An assistant calling the EmailHorizon MCP servercreate_campaign          { name: "Founders in fintech" }  ↳ A draft campaign. Nothing is sent until launch_campaign.set_campaign_sequence    { steps: [ 3 steps, 2 days apart ] }set_campaign_mailboxes   { mailbox_ids: [ maya@, sam@, jo@ ] }add_leads_to_campaign    { list_id: "Fintech founders" }launch_campaign          { campaign_id }  ↳ Real email goes out on the campaign's schedule. # Later, when replies come inlist_replies             { folder: "inbox" }send_reply               { reply_id, message }  ↳ Answers from the mailbox that received it.

FAQ

Questions, answered.

Questions

Answer

What is EmailHorizon?

Cold email software. You connect your own email accounts, add the people you want to reach and write a sequence. EmailHorizon sends it on schedule and stops the follow-ups when someone replies.

Private beta

Your inboxes. Your next campaign.

We open accounts a few teams at a time. Tell us how you send today and we will email you to set up your workspace.

We only use this to reply to you. Privacy Policy