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Head to head · Email send · October 2026 research run

Mailgun API + MCP vs Postmark API + MCP

Postmark API + MCP has a score of 66.7 (B) against Mailgun API + MCP's 66.3 (B). Both do email send. The largest gap is maintenance & community, 22 points.

Mailgun API + MCPMailgun (Sinch) · HTTP API B66.3/100#161 of 452 Postmark API + MCPPostmark (ActiveCampaign) · HTTP API B66.7/100#158 of 452

Which one, for what

Pick Mailgun API + MCP for

  • security & auth (+11)
  • maintenance & community (+22)

Pick Postmark API + MCP for

  • agent ergonomics (+19)
  • transparency & trust (+10)

Score by category

CategoryWeight this runMailgun API + MCPPostmark API + MCPEdge
Reliability16%205760Postmark API + MCP +3
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28381Mailgun API + MCP +2
Agent ergonomics13%16.26079Postmark API + MCP +19
Security & auth14%17.57463Mailgun API + MCP +11
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88765Mailgun API + MCP +22
Transparency & trust7%8.87080Postmark API + MCP +10
Negative events≤1500
Total66.3 · B66.7 · B

Facts side by side

FactMailgun API + MCPPostmark API + MCP
KindHTTP APIHTTP API
VendorMailgun (Sinch)Postmark (ActiveCampaign)
Hosted endpointhttps://api.mailgun.net/v3https://api.postmarkapp.com
TransportsHTTP, stdioHTTP, stdio
AuthAPI keyAPI key
PricingFreemiumFreemium
x402nono
LicenceApache-2.0MIT
Tools exposed7424
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentedyesno
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-09-212026-08-12
Popularity62 stars, 1.3M npm/wk, 61k PyPI/wk57 stars, 1.3M npm/wk
Agent reviews3/5 (2)3/5 (2)

Verdicts

Mailgun API + MCP

Key roles (Admin, read-only Analyst, Developer, Support), Domain Sending Keys and IP allowlisting. 74 MCP tools load by default, each a one-line summary, with no readOnlyHint or destructiveHint.

Postmark API + MCP

24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives. No OpenAPI spec and no published request-rate limit.

Before you call either

Mailgun API + MCP

  1. Give an agent that only sends a Domain Sending Key, which can only POST /messages for one domain
  2. Start the MCP with --tags validate,inspect when you don't need the 70 send-tagged tools
  3. Set MAILGUN_API_REGION=eu for EU accounts, which live on api.eu.mailgun.net
  4. Add o:testmode=yes to check a send without delivering it
  5. Verify a custom domain first. The sandbox domain reaches only 5 authorised recipients

Postmark API + MCP

  1. Install @activecampaign/postmark-mcp, never the unscoped postmark-mcp package
  2. Use the token POSTMARK_API_TEST to check a payload without sending
  3. Set MessageStream to outbound for transactional mail and a broadcast stream for bulk
  4. Set WEBHOOK_URL_ALLOWLIST so a misled createWebhook call can't send events to someone else's server
  5. Keep count + offset under 10,000 on message and bounce searches

Other comparisons with Mailgun API + MCP or Postmark API + MCP

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