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Head to head · Email send · October 2026 research run

Loops API + MCP vs SMTP2GO API + MCP

Loops API + MCP has a score of 63.1 (B) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is reliability, 43 points.

Loops API + MCPLoops (Astrodon Corporation) · HTTP API B63.1/100#209 of 452 SMTP2GO API + MCPSMTP2GO · HTTP API D53.2/100#336 of 452

Which one, for what

Pick Loops API + MCP for

  • reliability (+43)
  • schema & documentation (+23)
  • maintenance & community (+30)

Pick SMTP2GO API + MCP for

  • security & auth (+20)
  • payments & pricing (+10)

Score by category

CategoryWeight this runLoops API + MCPSMTP2GO API + MCPEdge
Reliability16%209047Loops API + MCP +43
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28259Loops API + MCP +23
Agent ergonomics13%16.26666even
Security & auth14%17.54060SMTP2GO API + MCP +20
Payments & pricing10%12.53040SMTP2GO API + MCP +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88353Loops API + MCP +30
Transparency & trust7%8.86972SMTP2GO API + MCP +3
Negative events≤15-3-3
Total63.1 · B53.2 · D

Facts side by side

FactLoops API + MCPSMTP2GO API + MCP
KindHTTP APIHTTP API
VendorLoops (Astrodon Corporation)SMTP2GO
Hosted endpointhttps://app.loops.so/api/v1https://api.smtp2go.com/v3
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthOAuth or keyAPI key
PricingFreemiumFreemium
x402nono
LicenceMITMIT
Tools exposednone5
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednoyes
llms.txtyesyes
MCP registryio.github.loops-so/loopsnot listed
Last release2026-09-032026-06-04
Popularity7 stars, 460k npm/wk9 stars, 1.8k npm/wk, 1.4k PyPI/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.

SMTP2GO API + MCP

API keys limited to chosen endpoints, with their own send rate. Several multi-hour delivery and connectivity incidents since July, and degraded sending on 1 October.

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

SMTP2GO API + MCP

  1. Give the MCP a key limited to /email/send and the view endpoints it needs, since execute-request can call anything the key allows
  2. Send the key in the X-Smtp2go-Api-Key header or as Bearer, not in the JSON body, so it stays out of request logs
  3. Verify a sender domain first. Free accounts without one are held to 25 emails an hour
  4. On 429, pause until calls return 200 again. Repeated errors time out your IP for at least a minute
  5. Check smtp2gostatus.com before blaming your payload for mail stuck as 'processed'

Other comparisons with Loops API + MCP or SMTP2GO API + MCP

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