Mailgun

39
Fair
Agent Native Score
Free TierAPI Key AuthOpenAPI Spec

Email delivery API for developers. Send, receive, and track emails. REST API with webhooks and email validation.

Categories: Communications · Email
#27 of 63 in Communications · #14 of 30 in Email
Checklist Breakdown

13 of 33 checks passed. 14 unscored.

Discovery 63%

Can an agent find and understand this tool without a web search?

✓ Published OpenAPI/Swagger spec
✗ Has llms.txt or llms-full.txt
✗ Has an MCP server (official or well-maintained)
✗ MCP server listed in a public registry
✓ API reference docs are publicly accessible
✓ Docs include runnable code examples
✓ Has a public changelog or release notes
✓ Has a public status page
Auth & Onboarding 50%

Can an agent create an account and get credentials without human intervention?

✗ Signup does not require CAPTCHA
✗ Signup does not require phone verification
✓ Supports API key auth (not only OAuth)
✗ API key obtainable without manual approval
✓ No mandatory billing info to start
✓ Can sign up without creating an organization
Pricing 100%

Can an agent operate autonomously without upfront payment or contracts?

✓ Has a free tier
✓ Usage-based pricing available
✓ No minimum contract or commitment
✓ Pricing page is public (no 'contact sales')
✓ Free tier sufficient for testing (not just a trial)
Agent Tooling Not yet scored

How well does the API work for non-human consumers?

— SDK available in 2+ languages
— Structured error responses (JSON with error codes)
— Idempotency support on write endpoints
— Pagination on list endpoints
— Webhook/event support
— Sandbox or test mode available
— Rate limit headers in responses
— Consistent REST resource naming
Reliability Not yet scored

Does the tool fail gracefully when an agent makes a mistake?

— Meaningful error messages (not just 500)
— 429 responses include Retry-After header
— Documented uptime SLA (99.9%+)
— Graceful degradation under rate limits
— Request IDs in responses for debugging
— API versioning supported
Reviewer Notes

Sandbox domain available for testing without DNS setup, but limited to 5 authorized recipients. Production requires domain verification. Free tier: 100 emails/day. Resend is a better developer-first alternative.

Top 10 Lists
Top 10 Communications → Top 10 Email →

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