MailerSend

MailerSend is a transactional email and SMS platform built for developers. Its v1 REST API covers email sending (single, bulk to 500 objects per request, and scheduled up to 72 hours out), SMTP relay, templates, sending domains and DNS verification, sender identities, recipients and five suppression lists, inbound routing, activity and analytics, email verification, DMARC and blocklist monitoring, SMS, and account/token administration. Authentication is a domain-scoped bearer token drawn from a 30-value scope vocabulary. MailerSend ships six official SDKs, an official Laravel driver, a Go CLI with an interactive TUI, a remote OAuth-protected MCP server exposing 127 tools, and its own published Agent Skill — but no machine-readable API contract and no idempotency guarantee.

MailerSend publishes 8 API contracts indexed on the APIs.io network, including Bulk Email API, Domains API, Email API, and 5 more. Tagged areas include Email, Transactional Email, SMTP, Marketing, and Communications.

The MailerSend catalog on APIs.io includes 1 event-driven AsyncAPI specification.

MailerSend’s developer surface includes engineering blog, authentication, documentation, API reference, getting-started guide, support, pricing, and 27 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

56.3/100 strong ▬ flat Agent 55/100 agent ready Front door AI 3/6 light saas Full breakdown ↓
scored 2026-10-17 · rubric v0.24.0

AccessSelf serve

1 published contract 1 MCP Servers 1 Agent Skills

Email Transactional Email SMTP Marketing Communications SMS Messaging Templates Webhook Email Verification Deliverability Analytics MCP

Kin Score

Kin Score How this is scored →
scored 2026-10-17 · rubric v0.24.0

Composite quality — 56.3/100 · strong

Contract Quality 10.1 / 19

Developer Ergonomics 11.8 / 15

Access Clarity 7.9 / 15

Operational Transparency 5.6 / 10

Contract Governance 0.4 / 9

Discoverability 5.6 / 8

Regulatory Posture 4.8 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 55/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 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 6 / 6

Agent Skills 5 / 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 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Telecommunications regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

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.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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/mailersend: 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 →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Communications (CPaaS)	covered	23.2	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

SMTP

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

APIs 8

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

MailerSend API

MailerSend API v1 provides RESTful endpoints for sending emails (single, bulk, scheduled), templates, domains, recipients, suppression lists, webhooks, analytics, SMS, and inbou...

MailerSend Bulk Email API

The Bulk Email API from MailerSend — 2 operation(s) for bulk email.

MailerSend Domains API

The Domains API from MailerSend — 2 operation(s) for domains.

MailerSend Email API

The Email API from MailerSend — 1 operation(s) for email.

MailerSend Messages API

The Messages API from MailerSend — 2 operation(s) for messages.

MailerSend Sender Identities API

The Sender Identities API from MailerSend — 1 operation(s) for sender identities.

MailerSend Templates API

The Templates API from MailerSend — 2 operation(s) for templates.

MailerSend Webhooks API

The Webhooks API from MailerSend — 2 operation(s) for webhooks.

Scroll for all 8

Open Collections 9

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

API Collection

OPEN COLLECTION

MailerSend Bulk Email API

OPEN COLLECTION

MailerSend Bulk Email Domains API

OPEN COLLECTION

MailerSend Bulk Email API

OPEN COLLECTION

MailerSend Bulk Email Messages API

OPEN COLLECTION

MailerSend Bulk Email Sender Identities API

OPEN COLLECTION

MailerSend Bulk Email Templates API

OPEN COLLECTION

MailerSend Bulk Email Webhooks API

OPEN COLLECTION

MailerSend API

OPEN COLLECTION

Scroll for all 9

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

MailerSend MCP Server

Remote MCP server at mcp.mailersend.com over streamable HTTP requiring OAuth; 127 tools listed.

MCP SERVER

Agent Skills 1

Packaged agent skills for driving this provider's APIs from an AI assistant.

MailerSend

AGENT SKILL

Pricing Plans 1

Published pricing tiers and plan structures.

Mailersend Plans Pricing

5 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Mailersend Rate Limits

5 limits

RATE LIMITS

FinOps 1

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

Mailersend Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Mailersend Webhooks

ASYNCAPI

OpenAPI Overlays 7

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Mailersend Bulk Email Api Overlay

2 actions · update · mailersend-bulk-email-api-openapi.yml

UNRECORDED

Mailersend Domains Api Overlay

2 actions · update · mailersend-domains-api-openapi.yml

UNRECORDED

Mailersend Email Api Overlay

2 actions · update · mailersend-email-api-openapi.yml

UNRECORDED

Mailersend Messages Api Overlay

2 actions · update · mailersend-messages-api-openapi.yml

UNRECORDED

Mailersend Sender Identities Api Overlay

2 actions · update · mailersend-sender-identities-api-openapi.yml

UNRECORDED

Mailersend Templates Api Overlay

2 actions · update · mailersend-templates-api-openapi.yml

UNRECORDED

Mailersend Webhooks Api Overlay

2 actions · update · mailersend-webhooks-api-openapi.yml

UNRECORDED

Scroll for all 7

Security Posture 2

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

Mailersend Authentication

http/oauth2 · 3 schemes

SECURITY

Mailersend Domain Security

TLSv1.3 · DMARC

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

Mailersend Scopes

30 scopes

SCOPES

Agentic Access 1

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

Mailersend Agentic Access

16 operations · 7 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

MCPServer

AgentSkill

LLMsTxt

WellKnown

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conventions

ErrorCatalog

ErrorCodes

Lifecycle

Conformance

DataModel

Webhooks

Scroll for all 7

Build 5

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

CLI

ToolCrosswalk

Access & Security 3

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

OAuthScopes

OAuthScopes

Operate 3

Status, limits, changes, and where to get help

RateLimits

RateLimits

Support

Support

StatusPage

StatusPage

Commercial 4

Pricing, plans, and the legal terms of use

Plans

FinOps

Pricing

PrivacyPolicy

Company 3

The organization behind the API

Blog

Blog

LinkedIn

Website

Website

Source (apis.yml)

aid: mailersend
url: https://raw.githubusercontent.com/api-evangelist/mailersend/refs/heads/main/apis.yml
name: MailerSend
kind: company
description: MailerSend is a transactional email and SMS platform built for developers. Its v1 REST API covers email sending
  (single, bulk to 500 objects per request, and scheduled up to 72 hours out), SMTP relay, templates, sending domains and
  DNS verification, sender identities, recipients and five suppression lists, inbound routing, activity and analytics, email
  verification, DMARC and blocklist monitoring, SMS, and account/token administration. Authentication is a domain-scoped bearer
  token drawn from a 30-value scope vocabulary. MailerSend ships six official SDKs, an official Laravel driver, a Go CLI with
  an interactive TUI, a remote OAuth-protected MCP server exposing 127 tools, and its own published Agent Skill — but no machine-readable
  API contract and no idempotency guarantee.
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: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: high
  source:
  - plans
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/mailersend.png
tags:
- Email
- Transactional Email
- SMTP
- Marketing
- Communications
- SMS
- Messaging
- Templates
- Webhook
- Email Verification
- Deliverability
- Analytics
- MCP
tags_raw:
- Email
- Transactional Email
- SMTP
- Marketing
- Communications
- SMS
- Messaging
- Templates
- Webhooks
- Email Verification
- Deliverability
- Analytics
- MCP
created: '2026-05-08'
modified: '2026-10-06'
specificationVersion: '0.23'
apis:
- aid: mailersend:mailersend-api
  name: MailerSend API
  description: MailerSend API v1 provides RESTful endpoints for sending emails (single, bulk, scheduled), templates, domains,
    recipients, suppression lists, webhooks, analytics, SMS, and inbound routing.
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Email
  - Transactional
  - REST
  properties:
  - type: Documentation
    url: https://developers.mailersend.com/
  - type: APIReference
    url: https://developers.mailersend.com/api/v1/email
- aid: mailersend:mailersend-bulk-email-api
  name: MailerSend Bulk Email API
  description: The Bulk Email API from MailerSend — 2 operation(s) for bulk email.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Bulk Email
  properties:
  - type: OpenAPI
    url: openapi/mailersend-bulk-email-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-bulk-email-api-overlay.yaml
- aid: mailersend:mailersend-domains-api
  name: MailerSend Domains API
  description: The Domains API from MailerSend — 2 operation(s) for domains.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Domains
  properties:
  - type: OpenAPI
    url: openapi/mailersend-domains-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-domains-api-overlay.yaml
- aid: mailersend:mailersend-email-api
  name: MailerSend Email API
  description: The Email API from MailerSend — 1 operation(s) for email.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Email
  properties:
  - type: OpenAPI
    url: openapi/mailersend-email-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-email-api-overlay.yaml
- aid: mailersend:mailersend-messages-api
  name: MailerSend Messages API
  description: The Messages API from MailerSend — 2 operation(s) for messages.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Message
  tags_raw:
  - Messages
  properties:
  - type: OpenAPI
    url: openapi/mailersend-messages-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-messages-api-overlay.yaml
- aid: mailersend:mailersend-sender-identities-api
  name: MailerSend Sender Identities API
  description: The Sender Identities API from MailerSend — 1 operation(s) for sender identities.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Sender Identities
  properties:
  - type: OpenAPI
    url: openapi/mailersend-sender-identities-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-sender-identities-api-overlay.yaml
- aid: mailersend:mailersend-templates-api
  name: MailerSend Templates API
  description: The Templates API from MailerSend — 2 operation(s) for templates.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Templates
  properties:
  - type: OpenAPI
    url: openapi/mailersend-templates-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-templates-api-overlay.yaml
- aid: mailersend:mailersend-webhooks-api
  name: MailerSend Webhooks API
  description: The Webhooks API from MailerSend — 2 operation(s) for webhooks.
  humanURL: https://developers.mailersend.com/
  baseURL: https://api.mailersend.com/v1
  tags:
  - Webhook
  tags_raw:
  - Webhooks
  properties:
  - type: OpenAPI
    url: openapi/mailersend-webhooks-api-openapi.yml
  - type: Overlay
    url: overlays/mailersend-webhooks-api-overlay.yaml
common:
- url: https://www.mailersend.com/blog
  type: Blog
- type: AgenticAccess
  url: agentic-access/mailersend-agentic-access.yml
- type: DomainSecurity
  url: security/mailersend-domain-security.yml
- type: Authentication
  url: authentication/mailersend-authentication.yml
- type: GitHubOrganization
  url: https://github.com/mailersend
- type: LinkedIn
  url: https://www.linkedin.com/company/mailersend
- type: Website
  url: https://www.mailersend.com/
- type: Documentation
  url: https://developers.mailersend.com/
- type: Plans
  url: plans/mailersend-plans-pricing.yml
- type: RateLimits
  url: rate-limits/mailersend-rate-limits.yml
- type: FinOps
  url: finops/mailersend-finops.yml
- type: DeveloperPortal
  url: https://developers.mailersend.com/
- type: APIReference
  url: https://developers.mailersend.com/api/v1/email
- type: GettingStarted
  url: https://developers.mailersend.com/sdk
- type: Support
  url: https://www.mailersend.com/help
- type: Pricing
  url: https://www.mailersend.com/pricing
- type: PrivacyPolicy
  url: https://www.mailersend.com/legal/privacy-policy
- type: StatusPage
  url: https://status.mailersend.com/
- type: Packages
  url: packages/mailersend-packages.yml
- type: SDKs
  url: packages/mailersend-packages.yml
- type: CLI
  url: cli/mailersend-cli.yml
- type: MCPServer
  url: mcp/mailersend-mcp.yml
- type: ToolCrosswalk
  url: mcp/mailersend-tool-crosswalk.yml
- type: AgentSkill
  url: skills/_index.yml
- type: LLMsTxt
  url: llms/mailersend-llms.txt
- type: WellKnown
  url: well-known/mailersend-well-known.yml
- type: OAuthScopes
  url: scopes/mailersend-scopes.yml
- type: Conventions
  url: conventions/mailersend-conventions.yml
- type: ErrorCatalog
  url: errors/mailersend-problem-types.yml
- type: ErrorCodes
  url: errors/mailersend-error-codes.yml
- type: Lifecycle
  url: lifecycle/mailersend-lifecycle.yml
- type: Conformance
  url: conformance/mailersend-conformance.yml
- type: DataModel
  url: data-model/mailersend-data-model.yml
- type: Webhooks
  url: asyncapi/mailersend-webhooks.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
x-enrichment:
  date: '2026-08-13'
  status: enriched
  artifacts_added: 26
  pass: local-v1
x-coverage:
  state: covered
  reason: docs-host-fully-open
  detail: developers.mailersend.com is entirely machine-readable (robots.txt allows all, 42-URL sitemap, a real llms.txt)
    and yielded rate limits, quotas, scopes, error codes, webhook events, CLI and MCP surfaces; the only wall was www.mailersend.com,
    which sits behind a Cloudflare "Just a moment..." bot challenge returning HTTP 429 to every automated request, so pricing,
    legal and trust pages could not be read.
  evidence:
  - url: https://developers.mailersend.com/llms.txt
    status: 200
  - url: https://mcp.mailersend.com/.well-known/oauth-protected-resource
    status: 200
  - url: https://mcp.mailersend.com/mcp
    status: 401
  - url: https://www.mailersend.com/pricing
    status: 429
  checked: '2026-08-13'

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