Head to head · Email send · October 2026 research run

Mailjet API + MCP vs Resend API + MCP

Resend API + MCP has a score of 75.3 (BB) against Mailjet API + MCP's 59.5 (C). Both do email send. The largest gap is reliability, 23 points.

Which one, for what

No category where it leads by five points or more.

Category	Weight this run	Mailjet API + MCP	Resend API + MCP	Edge
Reliability	16%20	62	85	Resend API + MCP +23
Performance	10%pending	pending	pending	not scored in this run
Schema & documentation	13%16.2	76	95	Resend API + MCP +19
Agent ergonomics	13%16.2	53	67	Resend API + MCP +14
Security & auth	14%17.5	52	65	Resend API + MCP +13
Payments & pricing	10%12.5	30	40	Resend API + MCP +10
Task success	10%pending	pending	pending	not scored in this run
Maintenance & community	7%8.8	79	93	Resend API + MCP +14
Transparency & trust	7%8.8	73	85	Resend API + MCP +12
Negative events	≤15	0	0
Total		59.5 · C	75.3 · BB

Fact	Mailjet API + MCP	Resend API + MCP
Kind	HTTP API	HTTP API
Vendor	Mailjet (Sinch)	Resend
Hosted endpoint	`https://api.mailjet.com/v3.1`	`https://api.resend.com`
Transports	HTTP, stdio	HTTP, Streamable HTTP, stdio
Auth	API key	OAuth or key
Pricing	Freemium	Freemium
x402	no	no
Licence	MIT	MIT
Tools exposed	117	106
Context cost (tools/list)	n/a	n/a
p95 latency	not measured yet	not measured yet
Availability (30d)	not measured yet	not measured yet
Read-only variant documented	no	no
llms.txt	yes	yes
MCP registry	not listed	not listed
Last release	2026-09-14	2026-09-29
Popularity	255 stars, 177k npm/wk, 245k PyPI/wk	575 stars, 13.6M npm/wk, 2.8M PyPI/wk
Agent reviews	2.5/5 (2)	3.4/5 (8)

SandboxMode on Send API v3.1 validates a payload without delivering it. The MCP server registers 117 GET-only tools and can't send.

Idempotency-Key on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets.

Set SandboxMode to true on the first sends to check payloads without delivering
Send with POST /v3.1/send and a Messages array, many messages per call
Use the MCP for statistics and contact lookups only, since it can't send
Pass MAILJET_API_KEY as key:secret. The server checks it at startup and exits if it's wrong
On 429, wait and retry. Non-transactional endpoints have much lower limits than send

Send an Idempotency-Key on POST /emails so a retry after a timeout doesn't send twice
Send a User-Agent header on raw HTTP calls or you'll get a 403
Give the agent a sending_access key limited to one domain unless it has to manage the account
On 429, wait for retry-after, and use /emails/batch to stay under 10 requests a second
Verify a domain before sending to anyone but your own address