Mailosaur website screenshot

Mailosaur

Mailosaur is an email and SMS testing platform for developers and QA teams. It provides a REST API for creating test inboxes, capturing and retrieving messages, running assertions, performing deliverability analysis, and integrating email and SMS testing into CI/CD pipelines. The platform supports authentication testing (TOTP/2FA), spam analysis, SPF/DKIM/DMARC validation, and connects via SMTP, POP3, and IMAP protocols.

Mailosaur publishes 7 APIs on the APIs.io network, including Analysis API, Devices API, Files API, and 4 more. Tagged areas include Email Testing, SMS Testing, Developer Tools, QA Automation, and CI/CD.

The Mailosaur catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

Mailosaur’s developer surface includes authentication, documentation, engineering blog, pricing, and 11 more developer resources.

🌐 Visit website 📡 Source on GitHub
49.0/100 developing ▬ flat Agent 31/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessPaidSelf serveFree trial⚡ Free to try
7 APIs
Email TestingSMS TestingDeveloper ToolsQA AutomationCI/CDSMTPTOTPDeliverability

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 49.0/100 · developing
Contract Quality 15.9 / 25
Developer Ergonomics 4.3 / 20
Commercial Clarity 11.6 / 20
Operational Transparency 2.7 / 13
Governance 7.0 / 12
Discoverability 7.4 / 10
Agent readiness — 31/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/mailosaur: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 7

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

Mailosaur Analysis API

Operations for analyzing the content and deliverability of an email, including SpamAssassin scoring and per-provider deliverability reports.

Mailosaur Devices API

Operations for managing virtual security devices and retrieving their current one-time passwords (OTPs), used to automate testing of app-based multi-factor authentication.

Mailosaur Files API

Operations for downloading the raw content associated with a message — file attachments, the full EML source of an email, and rendered email previews.

Mailosaur Messages API

Operations for finding, retrieving, creating, forwarding, replying to, and deleting the email and SMS messages received by your Mailosaur inboxes.

Mailosaur Previews API

Operations for discovering the email clients available for generating email previews (screenshots of an email rendered in real clients).

Mailosaur Servers API

Operations for creating and managing your Mailosaur inboxes (servers). Inboxes group your tests together, each with its own domain and SMTP/POP3/IMAP credentials.

Mailosaur Usage API

Operations for inspecting your account's usage limits and recent transactional usage. These endpoints require authentication with an account-level API key.

Scroll for all 7

Pricing Plans 1

Published pricing tiers and plan structures.

Mailosaur Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Mailosaur Rate Limits

0 limits

RATE LIMITS

FinOps 1

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

Mailosaur Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Mailosaur Context

38 classes · 7 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Mailosaur API Rules

6 rules · 4 warnings 2 info

SPECTRAL

JSON Schema 3

Standalone JSON Schema definitions for this provider's data models.

Device

2 properties

JSON SCHEMA

Message

13 properties

JSON SCHEMA

Server

4 properties

JSON SCHEMA

Examples 4

Example request and response payloads for these APIs.

Mailosaur Create Server Example

3 fields

EXAMPLE

Mailosaur Deliverability Report Example

3 fields

EXAMPLE

Mailosaur Get Otp Example

3 fields

EXAMPLE

Mailosaur Search Messages Example

3 fields

EXAMPLE

Security Posture 3

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

Mailosaur Authentication

http · 1 scheme

SECURITY

Mailosaur Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Mailosaur Trust Center

ISO 27001, PCI DSS, GDPR

SECURITY

Agentic Access 1

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

Mailosaur Agentic Access

28 operations · 13 acting

28 operations · 13 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

GitHubOrg
GitHubOrg

Access & Security 3

Authentication, authorization, and security posture

TrustCenter
TrustCenter
 DomainSecurity
DomainSecurity
 Authentication
Authentication

Operate 2

Status, limits, changes, and where to get help

StatusPage
StatusPage
 RateLimits
RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

Pricing
Pricing
 Plans
Plans
 FinOps
FinOps

Company 3

The organization behind the API

Website
Website
 LinkedIn
LinkedIn
 Blog
Blog

Other 1

Properties that don't map to a standard resource type

X
X

Source (apis.yml)

apis.yml Raw ↑ 
aid: mailosaur
name: Mailosaur
description: Mailosaur is an email and SMS testing platform for developers and QA teams. It provides a REST API for creating
  test inboxes, capturing and retrieving messages, running assertions, performing deliverability analysis, and integrating
  email and SMS testing into CI/CD pipelines. The platform supports authentication testing (TOTP/2FA), spam analysis, SPF/DKIM/DMARC
  validation, and connects via SMTP, POP3, and IMAP protocols.
type: Index
accessModel:
  pricing: paid
  onboarding: self-serve
  trial: true
  try_now: true
  public: false
  label: Paid (free trial) · 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/mailosaur.png
url: https://raw.githubusercontent.com/api-evangelist/mailosaur/refs/heads/main/apis.yml
created: 2026-06-13
modified: 2026-06-13
specificationVersion: '0.19'
tags:
- Email Testing
- SMS Testing
- Developer Tools
- QA Automation
- CI/CD
- SMTP
- TOTP
- Deliverability
apis:
- aid: mailosaur:mailosaur-analysis-api
  name: Mailosaur Analysis API
  description: Operations for analyzing the content and deliverability of an email, including SpamAssassin scoring and per-provider
    deliverability reports.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Analysis
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-analysis-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-devices-api
  name: Mailosaur Devices API
  description: Operations for managing virtual security devices and retrieving their current one-time passwords (OTPs), used
    to automate testing of app-based multi-factor authentication.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Devices
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-devices-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-files-api
  name: Mailosaur Files API
  description: Operations for downloading the raw content associated with a message — file attachments, the full EML source
    of an email, and rendered email previews.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Files
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-files-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-messages-api
  name: Mailosaur Messages API
  description: Operations for finding, retrieving, creating, forwarding, replying to, and deleting the email and SMS messages
    received by your Mailosaur inboxes.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Messages
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-messages-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-previews-api
  name: Mailosaur Previews API
  description: Operations for discovering the email clients available for generating email previews (screenshots of an email
    rendered in real clients).
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Previews
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-previews-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-servers-api
  name: Mailosaur Servers API
  description: Operations for creating and managing your Mailosaur inboxes (servers). Inboxes group your tests together, each
    with its own domain and SMTP/POP3/IMAP credentials.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Servers
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-servers-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
- aid: mailosaur:mailosaur-usage-api
  name: Mailosaur Usage API
  description: Operations for inspecting your account's usage limits and recent transactional usage. These endpoints require
    authentication with an account-level API key.
  humanURL: https://mailosaur.com/docs/api
  baseURL: https://mailosaur.com/api
  tags:
  - Usage
  properties:
  - type: OpenAPI
    url: openapi/mailosaur-usage-api-openapi.yml
  - type: Documentation
    url: https://mailosaur.com/docs/api
  - type: PostmanCollection
    url: https://www.postman.com/mailosaur/mailosaur/documentation/6961255-6cc72dff-f576-451a-9023-b82dec84f95d
common:
- type: AgenticAccess
  url: agentic-access/mailosaur-agentic-access.yml
- type: TrustCenter
  url: security/mailosaur-trust-center.yml
- type: DomainSecurity
  url: security/mailosaur-domain-security.yml
- type: Authentication
  url: authentication/mailosaur-authentication.yml
- type: Website
  url: https://mailosaur.com
- type: Documentation
  url: https://mailosaur.com/docs
- type: GitHubOrg
  url: https://github.com/mailosaur
- type: LinkedIn
  url: https://www.linkedin.com/company/mailosaur
- type: X
  url: https://x.com/mailosaur
- type: Blog
  url: https://mailosaur.com/blog
- type: Pricing
  url: https://mailosaur.com/pricing
- type: StatusPage
  url: https://status.mailosaur.com
- type: Plans
  url: plans/mailosaur-plans-pricing.yml
- type: RateLimits
  url: rate-limits/mailosaur-rate-limits.yml
- type: FinOps
  url: finops/mailosaur-finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com