# Best email delivery APIs for AI agents > Amazon SES (BB), Resend API + MCP (BB) and MailerSend (B) lead the 14 ranked email delivery APIs. Picks by need, strengths, weaknesses and prices from the Anchor benchmark. - Canonical: https://www.anchorterminal.com/best/email/ - Markdown: https://www.anchorterminal.com/best/email/index.md (~5,450 tokens) - Slim: https://www.anchorterminal.com/best/email/index.min.md (~1,330 tokens, same facts, less prose, for token-sensitive contexts) - JSON: https://www.anchorterminal.com/best/email/index.json (this page as data, same URL with Accept: application/json) - Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt) - API: https://www.anchorterminal.com/api/v1/index.json - Updated: 2026-10-08 The 10 highest-scoring of 14 email delivery APIs on the Anchor benchmark, with a pick for each need and where each one falls short. Scores come from public evidence, re-checked as vendors change. - Ranked: 14 · agent-ready (BB or better): 2 · accept x402: 0 · hosted endpoints: 14 - Full ranked table: https://www.anchorterminal.com/categories/email.md - Head-to-head comparisons: https://www.anchorterminal.com/compare/email/index.md (91) - Methodology: https://www.anchorterminal.com/benchmark/index.md ## The shortlist | # | Tool | Grade | Score | Best for | Price | Where | | --- | --- | --- | --- | --- | --- | --- | | 1 | [Amazon SES](https://www.anchorterminal.com/tools/amazon-ses.md) | BB | 75.1 | Teams already on AWS who send at volume and want IAM, CloudTrail and per-Region control. | $105 / mo | hosted | | 2 | [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md) | BB | 75.1 | Developers who want an agent to send, receive and manage templates from one MCP, and for teams that value tool descriptions written for models. | $20 / mo | hosted and local | | 3 | [MailerSend](https://www.anchorterminal.com/tools/mailersend.md) | B | 69.5 | An agent sending transactional email for an owner who wants scoped tokens, a hosted MCP server and low entry prices, with SMS and WhatsApp on the same API. | $7 / mo | hosted | | 4 | [Cloudflare Email Service](https://www.anchorterminal.com/tools/cloudflare-email-service.md) | B | 67.3 | Teams already on Cloudflare DNS and Workers that want transactional sending and inbound handling in one account at a low unit price. | $5 / mo | hosted | | 5 | [Mailtrap Email API + MCP](https://www.anchorterminal.com/tools/mailtrap.md) | B | 66.8 | Teams that want sending, a test sandbox and inbound mail under one token, with public OpenAPI specs and a free plan. | $15 / mo | hosted and local | | 6 | [Postmark API + MCP](https://www.anchorterminal.com/tools/postmark.md) | B | 66.5 | Transactional mail where deliverability and a small, well-annotated MCP matter more than a free tier. | $15 / mo | hosted and local | | 7 | [Mailgun API + MCP](https://www.anchorterminal.com/tools/mailgun.md) | B | 66.2 | Teams that want inbound routing, validation and per-key roles in one account, in US or EU regions. | $15 / mo | hosted and local | | 8 | [Twilio SendGrid](https://www.anchorterminal.com/tools/sendgrid.md) | B | 63.6 | Teams already on Twilio, or that want Marketing Campaigns, subusers and fine-grained keys in one account. | $19.95 / mo | hosted | | 9 | [Loops API + MCP](https://www.anchorterminal.com/tools/loops.md) | B | 62.7 | SaaS teams that send lifecycle and product email from one contact list and want an OAuth MCP. | $49 / mo | hosted | | 10 | [Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/tools/zoho-zeptomail.md) | C | 61.8 | Low-volume transactional senders who want prepaid credits without a monthly plan, and teams already on Zoho. | $30 / mo | hosted | ## Picks by need - Highest score overall: [Amazon SES](https://www.anchorterminal.com/tools/amazon-ses.md), BB, 75.1/100 on the benchmark. Also [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), BB, 75.1/100. - Schema & documentation: [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), 95/100 on schema & documentation, against 85 for the overall leader. - Agent ergonomics: [Postmark API + MCP](https://www.anchorterminal.com/tools/postmark.md), 79/100 on agent ergonomics, against 64 for the overall leader. - Maintenance & community: [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), 93/100 on maintenance & community, against 85 for the overall leader. - Transparency & trust: [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), 83/100 on transparency & trust, against 77 for the overall leader. - A hosted MCP endpoint: [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), remote MCP server, nothing to install. - The review panel's favourite: [Resend API + MCP](https://www.anchorterminal.com/tools/resend.md), 3.4/5 from 8 panel reviews. ## How to choose - Price per 1,000 emails: Compare the price per 1,000 emails at your expected volume, including any free allowance, since a headline rate can hide the cost of a low-volume agent. - Authentication records before sending: Check which SPF, DKIM and DMARC records a sending domain needs before the first send, since an agent that sends before they are live risks messages landing in spam. - Inbound mail delivery to agents: Check how inbound mail reaches the agent, whether by webhook with parsed body and attachments, since an agent that receives raw messages must parse replies itself. - Sandbox limits before live sending: Check what a sandbox or demo account can send, since an agent tested only in a restricted sandbox may pass every check and still fail in production. ## Each one in detail ### 1. Amazon SES, BB 75.1/100 AWS's email service for sending and receiving at scale, over the SES v2 API or SMTP, with templates, configuration sets, receipt rules and deliverability tooling. - Verdict: Sending starts at $0.10 per 1,000 emails on the a la carte plan. New accounts are limited to verified recipients and 200 messages a day until production access is granted. - Choose it for: Teams already on AWS who send at volume and want IAM, CloudTrail and per-Region control. - Strength: $0.10 per 1,000 emails a la carte, falling to $0.11 per 1,000 above 100 million on Essentials - Strength: IAM policies can limit a credential to SendEmail from one identity, and CloudTrail logs every call - Strength: Covered by an AWS SLA and in scope for SOC 1, 2 and 3 - Weakness: Sandbox limits new accounts to verified recipients and 200 messages a day until production access is granted - Weakness: SigV4 signing makes a plain curl or quick agent call awkward - Weakness: No SES-specific MCP server, and the AWS skill covers sending setup only - Price: $105 / mo · Auth: OAuth or key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/amazon-ses.md ### 2. Resend API + MCP, BB 75.1/100 Transactional and marketing email API with inbound receiving, templates, broadcasts and automations. - Verdict: `Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets. - Choose it for: Developers who want an agent to send, receive and manage templates from one MCP, and for teams that value tool descriptions written for models. - Strength: `Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours - Strength: MCP tool descriptions that say what each tool is for, what it isn't for and which tool to use instead - Strength: Hosted MCP with OAuth, and the same code on npm as resend-mcp under MIT - Weakness: 106 MCP tools load at once, with no toolsets - Weakness: No destructiveHint on the 16 remove, cancel, revoke and rotate tools - Weakness: Received mail reaches the model through the MCP with no prompt-injection guidance - Price: $20 / mo · Auth: OAuth or key · x402: no · Where: hosted and local - Full assessment: https://www.anchorterminal.com/tools/resend.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-resend.md ### 3. MailerSend, B 69.5/100 Transactional email service from MailerSend, Inc. with a REST API, SMTP relay, templates, inbound routing, webhooks and analytics, plus SMS and WhatsApp sending. Agents reach it with a scoped API token or through a hosted MCP server. - Verdict: API tokens carry any of 30 scopes and can be tied to one domain, rate limits are published with retry-after on every 429, and a 99.5 per cent SLA starts on the $35 Starter plan. Sends take no idempotency key, the Free plan allows 100 API requests a day, and the terms permit changes without notice. - Choose it for: An agent sending transactional email for an owner who wants scoped tokens, a hosted MCP server and low entry prices, with SMS and WhatsApp on the same API. - Strength: API tokens take any of 30 scopes, read or full by area, and can be limited to one sending domain - Strength: Rate limits published per endpoint, with retry-after and x-ratelimit headers on a 429 and a quota endpoint that isn't counted - Strength: 99.5 per cent monthly uptime SLA with service credits on Starter, Professional and Enterprise - Weakness: No idempotency key documented for POST /v1/email or the bulk endpoint - Weakness: Free plan is capped at 100 API requests a day and 500 emails a month, and asks for a card after account approval - Weakness: The terms allow MailerSend to change or end the service and the terms without notice, and to close an account without cause - Price: $7 / mo · Auth: OAuth or key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/mailersend.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-mailersend.md ### 4. Cloudflare Email Service, B 67.3/100 Cloudflare Email Service sends transactional email through a REST API, a Workers binding or SMTP, and routes inbound mail to Workers or verified addresses. Email Sending is in public beta and needs the Workers Paid plan for arbitrary recipients. - Verdict: Cloudflare API tokens can be limited to sending, given an expiry and restricted by IP address, and a public OpenAPI file covers 29 Email Sending operations. Sending is still in beta, with no SLA, no idempotency key and no published daily quota, and it needs a domain on Cloudflare DNS and the Workers Paid plan. - Choose it for: Teams already on Cloudflare DNS and Workers that want transactional sending and inbound handling in one account at a low unit price. - Strength: Public OpenAPI 3.0.3 file with 29 Email Sending and 46 Email Routing operations, plus llms.txt and a Markdown copy of every docs page - Strength: $0.35 per 1,000 emails after 3,000 included a month on Workers Paid. Sends rejected at the API boundary or blocked by the suppression list don't count - Strength: API tokens carry separate send and read permissions, an optional expiry and an IP address filter, and Workers bindings can be limited to named senders and recipients - Weakness: Email Sending has been in public beta since 16 April 2026. Cloudflare's terms let it remove a beta service at any time, and no SLA was found - Weakness: No idempotency key on `/email/sending/send`, in the docs or the OpenAPI file - Weakness: The daily sending quota for new accounts is described as conservative with no number. It can be read per account from `/email/sending/limits` - Price: $5 / mo · Auth: API key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/cloudflare-email-service.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-cloudflare-email-service.md ### 5. Mailtrap Email API + MCP, B 66.8/100 Email platform from Railsware Products Studio LLC for transactional and bulk sending, inbound mail, templates, contacts and sandbox testing. Agents reach it through a REST API, SMTP, SDKs, a CLI and a local MCP server. - Verdict: Public OpenAPI 3.1 specs, API tokens with per-resource permissions and expiry dates, and a free plan of 4,000 emails a month without a card support agent use. The MCP server loads 125 tools with no toolsets, no idempotency key was found for sends, and the status page records a sending outage of 1 hour 32 minutes on 1 August 2026. - Choose it for: Teams that want sending, a test sandbox and inbound mail under one token, with public OpenAPI specs and a free plan. - Strength: Ten public OpenAPI 3.1 specs in mailtrap/mailtrap-openapi, plus llms.txt, llms-full.txt and a Markdown copy of every docs page - Strength: API tokens carry per-resource permissions and an expiry date (365 days by default), and a reset keeps the old token valid for 12 hours - Strength: Free plan of 4,000 emails a month, with signup stated as needing no credit card, and overage rates published per 1,000 emails - Weakness: The MCP server registers 125 tools at once, with no toolsets, filtering or read-only mode - Weakness: No idempotency key for sends was found in the OpenAPI specs or the docs - Weakness: The status page records a sending outage of 1 hour 32 minutes on 1 August 2026 covering the Email Sending API, SMTP and Inbound Email - Price: $15 / mo · Auth: API key · x402: no · Where: hosted and local - Full assessment: https://www.anchorterminal.com/tools/mailtrap.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-mailtrap.md ### 6. Postmark API + MCP, B 66.5/100 Transactional email API with separate broadcast streams, templates, inbound parsing and bounce handling. - Verdict: 24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives. No OpenAPI spec and no published request-rate limit. - Choose it for: Transactional mail where deliverability and a small, well-annotated MCP matter more than a free tier. - Strength: 24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives - Strength: Prompt-injection guidance and a webhook URL allowlist in the MCP README - Strength: 45-day retention by default, two named subprocessors and a DPA in the terms - Weakness: No OpenAPI spec and no published request-rate limit - Weakness: Manual account approval before sending outside your own domains - Weakness: No SOC 2, ISO 27001, disclosure policy or security.txt found for Postmark itself - Price: $15 / mo · Auth: API key · x402: no · Where: hosted and local - Full assessment: https://www.anchorterminal.com/tools/postmark.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-postmark.md ### 7. Mailgun API + MCP, B 66.2/100 Email sending API with inbound routes, a Forwards API, templates, mailing lists, suppressions and address validation, in US and EU regions. - Verdict: 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. - Choose it for: Teams that want inbound routing, validation and per-key roles in one account, in US or EU regions. - Strength: Key roles (Admin, read-only Analyst, Developer, Support), Domain Sending Keys and IP allowlisting - Strength: OpenAPI 3.1 specs for `send`, `validate`, `optimize` and `inspect`, plus llms.txt - Strength: Inbound routes and a Forwards API (May 2026) for incoming mail - Weakness: 74 MCP tools load by default, each a one-line summary, with no readOnlyHint or destructiveHint - Weakness: 12 status incidents since 10 July, including 93 minutes of US validation API errors - Weakness: No general API rate limit published and no idempotency key for sends - Price: $15 / mo · Auth: API key · x402: no · Where: hosted and local - Full assessment: https://www.anchorterminal.com/tools/mailgun.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-mailgun.md ### 8. Twilio SendGrid, B 63.6/100 Email API v3 for transactional mail, with Inbound Parse, dynamic templates, suppressions and Marketing Campaigns. - Verdict: Restricted API keys with per-endpoint scopes, subuser keys and IP access management. No official MCP server that can send, only Twilio's docs search. - Choose it for: Teams already on Twilio, or that want Marketing Campaigns, subusers and fine-grained keys in one account. - Strength: Restricted API keys with per-endpoint scopes, subuser keys and IP access management - Strength: OpenAPI 3.1 specs for the whole v3 API - Strength: Inbound Parse and Marketing Campaigns in one account - Weakness: No official MCP server that can send, only Twilio's docs search - Weakness: Node and Python SDKs last released on 19 September 2025, Go on 29 May 2025 - Weakness: Free plan is a 60-day trial, not a standing free tier - Price: $19.95 / mo · Auth: API key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/sendgrid.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-sendgrid.md ### 9. Loops API + MCP, B 62.7/100 Email platform for SaaS companies with one API for contacts, events, campaigns, workflows and transactional email, priced by subscribed contacts rather than sends. - Verdict: No status incidents in the last 90 days. No scoped or read-only keys, and no read-only MCP mode. - Choose it for: SaaS teams that send lifecycle and product email from one contact list and want an OAuth MCP. - Strength: No status incidents in the last 90 days - Strength: `Idempotency-Key` on event and transactional sends - Strength: Hosted MCP with OAuth, listed in the official MCP registry - Weakness: No scoped or read-only keys, and no read-only MCP mode - Weakness: Transactional sends need a published template, no ad hoc HTML - Weakness: No inbound email or reply handling - Price: $49 / mo · Auth: OAuth or key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/loops.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-loops.md ### 10. Zoho CPaaS (formerly ZeptoMail), C 61.8/100 Transactional email service from Zoho, renamed from ZeptoMail to Zoho CPaaS in September 2026. It sends application email through a REST API or SMTP relay, with templates, domain management, suppression lists, logs and webhooks. - Verdict: A public OpenAPI 3.0 file covers all 42 operations, and each Agent has its own send-only key. Email costs $2.50 per 10,000 with the first credit free. No API rate limit, 429 handling, idempotency key or SLA was found in the reviewed documentation, and new accounts wait for a manual review. - Choose it for: Low-volume transactional senders who want prepaid credits without a monthly plan, and teams already on Zoho. - Strength: Public OpenAPI 3.0.3 file with 42 operations, plus llms.txt and a Markdown copy of every help page - Strength: Send keys are per Agent and per channel and can only send. Management calls use OAuth with READ, CREATE, UPDATE and DELETE scopes per resource - Strength: Published price of $2.50 per credit of 10,000 emails, valid six months, with the first credit free - Weakness: No API rate limit, 429 behaviour or Retry-After was found in the reviewed documentation or the OpenAPI file - Weakness: No idempotency key on send. `client_reference` is a tracking label only - Weakness: Every new account is reviewed by Zoho staff, which the docs say takes two business days, before credits can be bought - Price: $30 / mo · Auth: OAuth or key · x402: no · Where: hosted - Full assessment: https://www.anchorterminal.com/tools/zoho-zeptomail.md - Against #1: https://www.anchorterminal.com/compare/amazon-ses-vs-zoho-zeptomail.md 4 more are ranked in the full table: https://www.anchorterminal.com/categories/email.md ## Head to head - [Amazon SES vs Resend API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-resend.md) - [Amazon SES vs MailerSend](https://www.anchorterminal.com/compare/amazon-ses-vs-mailersend.md) - [Amazon SES vs Cloudflare Email Service](https://www.anchorterminal.com/compare/amazon-ses-vs-cloudflare-email-service.md) - [Amazon SES vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-mailtrap.md) - [MailerSend vs Resend API + MCP](https://www.anchorterminal.com/compare/mailersend-vs-resend.md) - [Cloudflare Email Service vs Resend API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-resend.md) - [Mailtrap Email API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailtrap-vs-resend.md) - [Cloudflare Email Service vs MailerSend](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailersend.md) - [MailerSend vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/mailersend-vs-mailtrap.md) - [Cloudflare Email Service vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailtrap.md) ## Questions ### What are the highest-rated email delivery APIs for AI agents? Amazon SES has the highest benchmark score of the 14 ranked email delivery APIs, 75.1 (BB). Resend API + MCP is second with 75.1 (BB). ### How many email delivery APIs are agent-ready? 2 of the 14 ranked here grade BB or better, the bar for agent-ready on the Anchor benchmark. ### Which email delivery APIs accept x402 payments? None of the ranked listings here accepts x402 for its main call yet. ### How is this list ranked? By the Anchor benchmark score out of 100, a weighted mean of the scored categories minus deductions for negative events, from public evidence re-checked as vendors change. Listings cannot pay for a place. The latest assessment behind this page is from 8 October 2026. ## How this list is made The order is the Anchor benchmark score, the same number as on each listing. Each listing is graded from public evidence against the benchmark checklist, and the picks are worked out from those grades, prices and facts. No listing pays for its place, and paid audits or listing help never change a score.