MailPace

MailPace is a fast, privacy-focused transactional email API for developers. It delivers application email - password resets, receipts, notifications - over a simple HTTPS REST API and SMTP, with DKIM-verified sending domains, Ed25519-signed webhooks, and EU-based hosting.

MailPace publishes 3 APIs on the APIs.io network: API Tokens API, Domains API, and Send API. Tagged areas include Email, Transactional Email, Messaging, SMTP, and Privacy.

MailPace’s developer surface includes authentication, documentation, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub

35.8/100 thin ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-14 · rubric v0.22.0

AccessFreeSelf serve⚡ Free to try

1 APIs

Email Transactional Email Messaging SMTP Privacy

Kin Score

Kin Score How this is scored →
scored 2026-09-14 · rubric v0.22.0

Composite quality — 35.8/100 · thin

Contract Quality 12.4 / 23

Developer Ergonomics 5.1 / 18

Access Clarity 5.2 / 18

Operational Transparency 4.0 / 12

Contract Governance 0.0 / 11

Discoverability 6.2 / 9

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 26/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/mailpace: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 4

Individual APIs this provider publishes, each with its own machine-readable definition.

MailPace Webhooks API

Delivers outbound, Ed25519-signed event callbacks (email.queued, email.delivered, email.deferred, email.bounced, email.spam) to your endpoints. Configured per domain in the Mail...

MailPace API Tokens API

Manage per-domain API tokens.

MailPace Domains API

Manage sending domains and DKIM verification.

MailPace Send API

Send transactional email.

Open Collections 5

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

MailPace API Tokens API

OPEN COLLECTION

MailPace API Tokens Domains API

OPEN COLLECTION

MailPace API Tokens Send API

OPEN COLLECTION

MailPace API

OPEN COLLECTION

Pricing Plans 1

Published pricing tiers and plan structures.

Mailpace Plans Pricing

2 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Mailpace Rate Limits

3 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Mailpace Finops

FINOPS

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Mailpace Authentication

apiKey · 2 schemes

SECURITY

Mailpace Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Mailpace Agentic Access

11 operations · 7 acting · 1 human-in-the-loop

11 operations · 7 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

LinkedIn

Website

Website

Source (apis.yml)

aid: mailpace
url: https://raw.githubusercontent.com/api-evangelist/mailpace/refs/heads/main/apis.yml
name: MailPace
kind: company
description: MailPace is a fast, privacy-focused transactional email API for developers. It delivers application email - password
  resets, receipts, notifications - over a simple HTTPS REST API and SMTP, with DKIM-verified sending domains, Ed25519-signed
  webhooks, and EU-based hosting.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: free
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  label: Free · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/mailpace.png
tags:
- Email
- Transactional Email
- Messaging
- SMTP
- Privacy
created: '2026-06-20'
modified: '2026-06-20'
specificationVersion: '0.23'
apis:
- aid: mailpace:mailpace-webhooks-api
  name: MailPace Webhooks API
  tags:
  - Webhook
  - Event
  - Ed25519
  tags_raw:
  - Webhooks
  - Events
  - Ed25519
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://docs.mailpace.com/guide/webhooks/
  baseURL: https://app.mailpace.com/api/v1
  properties:
  - url: https://docs.mailpace.com/guide/webhooks/
    type: Documentation
  - url: review.yml
    type: Review
  description: Delivers outbound, Ed25519-signed event callbacks (email.queued, email.delivered, email.deferred, email.bounced,
    email.spam) to your endpoints. Configured per domain in the MailPace dashboard; the public verification key is exposed
    on the domain object.
- aid: mailpace:mailpace-api-tokens-api
  name: MailPace API Tokens API
  description: Manage per-domain API tokens.
  humanURL: https://docs.mailpace.com/reference/send/
  baseURL: https://app.mailpace.com/api/v1
  tags:
  - API Tokens
  properties:
  - type: OpenAPI
    url: openapi/mailpace-api-tokens-api-openapi.yml
  - type: Documentation
    url: https://docs.mailpace.com/reference/send/
  - type: APIReference
    url: https://docs.mailpace.com/reference/overview/
  - type: Documentation
    url: https://docs.mailpace.com/reference/domains/
- aid: mailpace:mailpace-domains-api
  name: MailPace Domains API
  description: Manage sending domains and DKIM verification.
  humanURL: https://docs.mailpace.com/reference/send/
  baseURL: https://app.mailpace.com/api/v1
  tags:
  - Domains
  properties:
  - type: OpenAPI
    url: openapi/mailpace-domains-api-openapi.yml
  - type: Documentation
    url: https://docs.mailpace.com/reference/send/
  - type: APIReference
    url: https://docs.mailpace.com/reference/overview/
  - type: Documentation
    url: https://docs.mailpace.com/reference/domains/
- aid: mailpace:mailpace-send-api
  name: MailPace Send API
  description: Send transactional email.
  humanURL: https://docs.mailpace.com/reference/send/
  baseURL: https://app.mailpace.com/api/v1
  tags:
  - Send
  properties:
  - type: OpenAPI
    url: openapi/mailpace-send-api-openapi.yml
  - type: Documentation
    url: https://docs.mailpace.com/reference/send/
  - type: APIReference
    url: https://docs.mailpace.com/reference/overview/
  - type: Documentation
    url: https://docs.mailpace.com/reference/domains/
common:
- type: AgenticAccess
  url: agentic-access/mailpace-agentic-access.yml
- type: DomainSecurity
  url: security/mailpace-domain-security.yml
- type: Authentication
  url: authentication/mailpace-authentication.yml
- type: GitHubOrganization
  url: https://github.com/mailpace
- type: LinkedIn
  url: https://www.linkedin.com/company/mailpace
- type: Website
  url: https://mailpace.com
- type: Documentation
  url: https://docs.mailpace.com
- type: Plans
  url: plans/mailpace-plans-pricing.yml
- type: RateLimits
  url: rate-limits/mailpace-rate-limits.yml
- type: FinOps
  url: finops/mailpace-finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This provider

curl "https://apis.io/api/v1/providers/mailpace"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/mailpace/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/mailpace/evidence"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.