Warmerly
REST API and webhooks on the Agency plan only; an MCP server on every plan.
Warmerly
Mailreach
One-to-one · API access
API access
One row, in depth: what each tool does, the verified numbers, and who each suits.
Mailreach details read from its pricing page and script, home page, product pages, terms, privacy policy and docs on 21 October 2026.
Warmerly
REST API and webhooks on the Agency plan only; an MCP server on every plan.
Mailreach
A documented REST API, a spam test API, Zapier, Make and an MCP connection; plans not stated.
The short answer
API access, in one look.
Warmerly's API is on the Agency plan only ($179 a month), while Mailreach has a REST API documented at docs.mailreach.co that can run spam tests, manage inboxes and pull statistics, plus webhooks, Zapier and Make, without saying which plans include it. Both offer an MCP connection. Last checked 22 October 2026.
MailreachMailreach ahead on this row
A documented REST API, a spam test API, Zapier, Make and an MCP connection; plans not stated.
The picture
Drawn side by side.
Who gets the API
As each describes it
WarmerlyMailreach
Warmerly
Agency planAPI key and webhooksYour app
Mailreach
Plan not statedAPI key in a headerZapier, Make and webhooks
Both offer an MCP connection: Warmerly on every plan, Mailreach in its docs.
How Warmerly does it
Warmerly, in detail.
Keys, a rate limit you set, signed health webhooks and an MCP server, with the API on the Agency plan only.
01
Agency plan only
API keys, the REST API and webhooks need the Agency plan. Free, Starter and Growth get a 403 error. The Agency 7-day trial includes the API.
Warmerly product, checked 21 October 2026
02
60 requests a minute by default
Each key has its own limit, 60 a minute by default, set at creation from 1 to 120, and capped at 120 on every plan.
Warmerly product, checked 21 October 2026
03
Health webhooks
Signed webhooks send mailbox health events such as score drops, authentication failures and DNS changes. They do not send opens or replies.
Warmerly product, checked 21 October 2026
04
An MCP server on every plan
Claude, ChatGPT and other MCP clients can work in a workspace on every plan, including Free.
Warmerly product, checked 21 October 2026
05
Two headers on most calls
A key goes in X-Api-Key. Mailboxes, campaigns and inbox data belong to a project, so most endpoints also need an X-Project-Id header.
Warmerly product, checked 21 October 2026
06
Keys are shown once
A key starts with wmv_ and the full secret is returned only when you create it. Warmerly keeps a hash, so a lost key is revoked and replaced. Each user can hold 10 active keys.
Warmerly product, checked 21 October 2026
07
Sixteen webhook event types
They cover score drops, a score hitting its floor, authentication and SMTP or IMAP failures, DNS changes, auto-pauses and resumes, a mailbox ageing in and OAuth disconnects.
Warmerly product, checked 21 October 2026
08
Deliveries are signed
Every delivery carries X-Warmerly-Signature, an HMAC-SHA256 of the raw body made with the subscription secret, which you recompute to verify it.
Warmerly product, checked 21 October 2026
09
A sweep every 5 minutes
Webhooks are sent by a background sweep that polls for new events every 5 minutes, not in real time. Each delivery is tried 3 times with a 5 second timeout.
Warmerly product, checked 21 October 2026
10
Failing endpoints are switched off
A subscription is disabled after 10 consecutive sweeps in which a delivery failed. You re-enable it with a PATCH. Redirects are never followed and targets must be public https URLs.
Warmerly product, checked 21 October 2026
11
A key stops working after a downgrade
A key is only accepted while the workspace is on Agency, so every endpoint returns 403 agency_plan_required after a downgrade, and webhook deliveries pause.
Warmerly product, checked 21 October 2026
12
One error shape
Authenticated errors return a code, a message and details, and a rate limit returns 429 too_many_requests. A rare unhandled exception returns a bare string instead.
Warmerly product, checked 21 October 2026
How Mailreach does it
Mailreach, in detail.
A REST API with public docs, a spam test API, webhooks, Zapier and Make, and an MCP connection.
01
A REST API with public docs
The docs say it can run spam tests, connect and manage inboxes for warming and monitoring, and pull deliverability statistics.
docs.mailreach.co · read 21 October 2026
02
A key in a header
Requests send an API key in an X-Api-Key header, and a missing key returns 401. The docs say the API is free to call.
docs.mailreach.co · read 21 October 2026
03
Zapier, Make and webhooks
The API page lists Zapier and Make, and the docs mention webhooks and alerts.
mailreach.co/email-warmup-api · read 21 October 2026
04
An MCP connection
The docs say you can connect Claude, ChatGPT, Claude Code or Cursor to your project.
docs.mailreach.co · read 21 October 2026
05
A spam test API
A separate REST API runs automatic spam tests on a schedule and returns a score, placement insights and recommendations.
mailreach.co/email-spam-test-api · read 21 October 2026
06
A stated base URL and style
The API is REST with JSON bodies and responses, at api.mailreach.co/api/v1. You need an account and at least one project, and the key is on the project's Settings tab.
docs.mailreach.co · read 22 October 2026
07
Status codes and retry advice
It lists 200, 201, 400, 401, 403, 404, 422, 429 and 5xx, and says to back off on 429 and use exponential backoff on 5xx.
docs.mailreach.co · read 22 October 2026
08
No idempotency keys
The docs say the API does not currently support idempotency keys, so you check for an existing resource before creating one.
docs.mailreach.co · read 22 October 2026
09
Pagination
List endpoints take page and per_page and return results in descending creation order.
docs.mailreach.co · read 22 October 2026
10
How it is billed
The API is free. Warming and monitoring are billed per connected inbox each month, and the spam checker is billed one credit per test.
docs.mailreach.co · read 22 October 2026
11
Spam tests, one-off or scheduled
One-time tests create a test, send the email and fetch the placement report. Automated tests schedule recurring placement checks from a connected inbox. The example call is POST /spam_tests.
docs.mailreach.co · read 22 October 2026
12
Real-time webhooks and daily statistics
The docs describe webhook notifications in real time and daily time-series deliverability statistics.
docs.mailreach.co · read 22 October 2026
What Mailreach does not say
We looked, and found no statement on these. That is about its published pages only, not about the product.
- Which plans include API access
- Rate limits
- The full list of endpoints
- Webhook event types and payload format
- Whether the API can add a mailbox or start warming
- Default and maximum page size
- Any SDKs
Where the sources disagree
We report each version rather than pick one.
- Its docs show a Bearer prefix inside an X-Api-Key header, which is unusual, so test a request before relying on it.
The numbers
Only what we could verify.
| Measure | Warmerly | Mailreach |
|---|---|---|
| API access | REST API and webhooks on the Agency plan only; an MCP server on every plan. | A documented REST API, a spam test API, Zapier, Make and an MCP connection; plans not stated. |
| Requests a minute per key | 60 by default, up to 120 | Not stated |
| Plans with API access | Agency only | Not stated |
| MCP connection | Every plan | Stated in its docs |
| Active keys per user | 10 | Not stated |
| Webhook delivery attempts | 3, with a 5 second timeout | Not stated |
| Webhook event types | 16 | Not stated |
| Cost of calling the API | Included with Agency | Free to call, billed per inbox and per test |
In practice
What it means for you.
Our reading of the facts above. Not a promise, and not the only reasonable reading.
If an API is central, Mailreach looks wider
It documents warm-up and spam test APIs plus Zapier and Make. Check which plan you need before you rely on it.
Warmerly's API is for fleets
Agency covers 100 mailboxes and the API together, so it suits teams that manage many.
Push or pull
Warmerly's webhooks go out on a sweep every 5 minutes, so an alert can arrive several minutes after the event. Mailreach's docs say real-time webhooks, though they do not list the events. If minute-level alerts matter, test both.
What 60 requests a minute buys
At the default 60 a minute a key makes 3,600 calls an hour, and at the cap of 120 it makes 7,200. Reading 100 mailboxes one request each would take under two minutes at the default.
Trying it before you pay
The Agency 7-day trial includes the API, so you can build an integration first. Mailreach's API is free to call but needs an account with a project, and the spam checker costs one credit per test.
Planning for a downgrade
On Warmerly a downgrade from Agency stops every key and pauses webhooks, with nothing deleted. Keep a note of which jobs depend on a key.
Retries without idempotency keys
Mailreach says to check for an existing resource before creating one, because it has no idempotency keys. Build that check into any job that creates tests.
Who it suits
Pick the one that fits.
Warmerly
Warmerly is the better fit if
- You want published request limits
- You want MCP on every plan
- You work at Agency size
- You want signed health webhooks with a clear retry rule
- You want to set a rate limit per key
Mailreach
Mailreach is the better fit if
- You want a documented API for warm-up and spam tests
- You use Zapier or Make
- You want API and spam test automation
- You want a documented spam test API
- You want pay-as-you-go tests alongside an API with no charge for calls
- You use Zapier or Make for deliverability reports
Questions
Does Mailreach have an API?
Yes: a REST API documented at docs.mailreach.co, and a separate spam test API. It does not say which plans include API access (read 21 October 2026).
Which Warmerly plan has the API?
Agency, at $179 a month. Free, Starter and Growth get a 403 error. MCP works on every plan.
Does Mailreach charge for API calls?
Its docs say the API itself is free. Warming and monitoring are billed per connected inbox and the spam checker one credit per test (docs.mailreach.co, read 22 October 2026).
How does Warmerly sign webhooks?
Each delivery has an X-Warmerly-Signature header, a hex HMAC-SHA256 of the raw body using the subscription secret, shown in full only at creation.
What happens if my webhook endpoint is down?
Each event is tried 3 times. A failed event is not sent again, and the subscription is disabled after 10 consecutive failed sweeps until you re-enable it.
Sources
Mailreach pages were read on 21 October 2026. Plans and wording change, so check the vendor's own page before you decide. Warmerly details come from the product as it runs today.
More features
- All features
- Starting price (per month)
- Pricing model
- Cost at 5, 25 and 100 mailboxes
- Free plan or trial
- Warmup network size
- Daily warmup volume
- Spam rescue
- Spam test and inbox placement
- SPF, DKIM, DMARC and blocklist checks
- Alerts
- Campaign sending
- Mailbox providers
- Agencies and client mailboxes
- Data hosting and security
See it on your own mailbox.
Connect a mailbox. Warmerly runs alongside whatever you send from now, so you can compare before you move anything.
Free plan, no card. Paid plans: 7-day trial, first charge on day 8.