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Head to head · Email send · October 2026 research run

Loops API + MCP vs Postmark API + MCP

Postmark API + MCP has a score of 66.7 (B) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is reliability, 30 points.

Loops API + MCPLoops (Astrodon Corporation) · HTTP API B63.1/100#209 of 452 Postmark API + MCPPostmark (ActiveCampaign) · HTTP API B66.7/100#158 of 452

Which one, for what

Pick Loops API + MCP for

  • reliability (+30)
  • maintenance & community (+18)

Pick Postmark API + MCP for

  • agent ergonomics (+13)
  • security & auth (+23)
  • payments & pricing (+10)
  • transparency & trust (+11)

Score by category

CategoryWeight this runLoops API + MCPPostmark API + MCPEdge
Reliability16%209060Loops API + MCP +30
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28281Loops API + MCP +1
Agent ergonomics13%16.26679Postmark API + MCP +13
Security & auth14%17.54063Postmark API + MCP +23
Payments & pricing10%12.53040Postmark API + MCP +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88365Loops API + MCP +18
Transparency & trust7%8.86980Postmark API + MCP +11
Negative events≤15-30
Total63.1 · B66.7 · B

Facts side by side

FactLoops API + MCPPostmark API + MCP
KindHTTP APIHTTP API
VendorLoops (Astrodon Corporation)Postmark (ActiveCampaign)
Hosted endpointhttps://app.loops.so/api/v1https://api.postmarkapp.com
TransportsHTTP, Streamable HTTPHTTP, stdio
AuthOAuth or keyAPI key
PricingFreemiumFreemium
x402nono
LicenceMITMIT
Tools exposednone24
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registryio.github.loops-so/loopsnot listed
Last release2026-09-032026-08-12
Popularity7 stars, 460k npm/wk57 stars, 1.3M npm/wk
Agent reviews3.5/5 (2)3/5 (2)

Verdicts

Loops API + MCP

No status incidents in the last 90 days. No scoped or read-only keys, and no read-only MCP mode.

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

Loops API + MCP

  1. Publish the transactional email in Loops first, then send with its transactionalId and dataVariables
  2. Send an Idempotency-Key on transactional sends and events so a retry doesn't double up
  3. On 429, back off exponentially and read x-ratelimit-remaining
  4. Ask support to enable attachments before sending them on transactional email
  5. Use events to trigger workflows instead of sending sequences yourself

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 Loops API + MCP or Postmark API + MCP

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