Cold outreach built for deliverability at scale.
Send from mailboxes your team already owns, verify every address before it enters a queue, and pause sequences automatically when a prospect replies.
No card required · 14 days · Every send authenticated · No shared IP pools
One sequence, distributed across every connected mailbox, each held under its own daily cap.
Sends from mailboxes you own
- Outlook
- Any SMTP / IMAP host
How It Works
From raw list to booked reply, on infrastructure your team controls.
Load and clean the list
Import CSVs or build filtered segments, then run six verification stages so invalid addresses never reach a send queue.
Connect mailboxes, launch sequences
Connect your Gmail or Workspace accounts and distribute volume across them using randomised send intervals and A/B variants.
Reply lands, follow-ups stop
Herald Engine watches the connected inbox and halts the remaining steps for that prospect the moment they respond.
Everything the send path needs
Verification, warmup, sequencing, and reply detection in a single system, so deliverability is a property of the platform rather than an ongoing operational burden.
Campaign sending
Per-mailbox daily caps, throttled delivery, and merge-field validation that blocks a send rather than delivering an empty variable.
Sequences with auto-pause
Multi-step follow-ups on randomised intervals. A reply halts the remaining steps in that thread automatically.
Six-stage verification
Syntax, domain, MX, catch-all, role, and mailbox checks run before an address is allowed into a send queue.
Mailbox warmup
A 21-day ramp from 5 to 50 sends a day, so a new domain builds reputation before it carries real volume.
A/B variants
Test subject lines and bodies with per-variant reporting, and promote the winner without rebuilding the sequence.
Open and click tracking
Per-recipient engagement on your own tracking domain, exportable to the rest of your stack.
Unified inbox
Replies from every connected mailbox in one thread view, answerable without leaving the platform.
Dynamic lists
Segments that re-evaluate as engagement changes, so a list is never stale at launch.
Lead scoring
Opens, clicks, and replies resolve into a score that prioritises the contacts most likely to convert.
- SPF
- DKIM
- DMARC
- TLS
Every message is signed and carried over authenticated channels, sent from a domain you own, under per-mailbox daily caps.
Pricing
Simple, transparent pricing
Start free for 14 days. No credit card required. Upgrade when you’re ready.
Starter
Billed annually · 2 months free
Start free trial- 3 sending accounts
- 500 emails/day
- Verification, 100/day
- Auto warmup + unified inbox
Professional
Billed annually · 2 months free
Start free trial- 10 sending accounts
- 2,000 emails/day
- Unlimited verification
- A/B testing + custom tracking domain
Business
Billed annually · 2 months free
Start free trial- Unlimited sending accounts
- 5,000 emails/day
- API, webhooks and CRM sync
- Priority support
Enterprise
Billed annually · 2 months free
Start free trial- Everything in Business
- 10,000 emails/day
- White-label + lead scoring
- Dedicated support
Compare plans
| Feature | Starter | Professional | Business | Enterprise |
|---|---|---|---|---|
| Sending | ||||
| Sending accounts | 3 | 10 | Unlimited | Unlimited |
| Emails per day | 500 | 2,000 | 5,000 | 10,000 |
| Auto warmup | Included | Included | Included | Included |
| Custom tracking domain | Not included | Included | Included | Included |
| Lists & verification | ||||
| Email verification | 100/day | Unlimited | Unlimited | Unlimited |
| Lead list management | Included | Included | Included | Included |
| Smart lead lists | Not included | Included | Included | Included |
| Campaigns | ||||
| Drip campaigns & auto-pause | Included | Included | Included | Included |
| A/B testing | Not included | Included | Included | Included |
| Open & click tracking | Included | Included | Included | Included |
| Unified inbox | Included | Included | Included | Included |
| Analytics | ||||
| Advanced analytics | Not included | Included | Included | Included |
| CSV export | Not included | Included | Included | Included |
| Lead scoring | Not included | Not included | Not included | Included |
| Integrations | ||||
| API access | Not included | Not included | Included | Included |
| Webhook integrations | Not included | Not included | Included | Included |
| CRM sync | Not included | Not included | Included | Included |
| Team & support | ||||
| Team members | Not included | 3 | 5 | Unlimited |
| Priority support | Not included | Not included | Included | Included |
| Dedicated support | Not included | Not included | Not included | Included |
| White-label branding | Not included | Not included | Not included | Included |
| Custom integrations | Not included | Not included | Not included | Included |
FAQ
Frequently asked questions
Sending, deliverability, billing, and setup. If something is not covered here, our team will answer directly.
Evaluating Herald Engine?
Start the trial and connect a mailbox. No card is required, and nothing sends until you launch a sequence.
Start free trialFrom the blog
Field notes on deliverability
- Deliverability
Why cold email lands in spam, and what actually moves the needle
Most deliverability advice treats spam placement as a copywriting problem. It is usually an infrastructure problem, and the fixes are unglamorous.
3 min read - Deliverability
Mailbox warmup: what the 21-day ramp is actually doing
Warmup is often described as “building trust” without saying what that means. Here is the mechanism, and why the schedule matters more than the volume.
2 min read - Data quality
Six-stage email verification, explained stage by stage
A verification result is only as useful as the checks behind it. Here is what each stage proves, what it cannot prove, and where the false confidence hides.
2 min read