MailerSend

What our check kept, up to 60 lines or 6 KB

User-agent: *
Disallow: /cp/
Content-Signal: search=yes, ai-input=yes, ai-train=no

Sitemap: https://www.mailersend.com/sitemap.xml

How we test this:

• We read robots.txt and check it doesn't disallow / for the agents that fetch for a user or find sites for AI search: ChatGPT-User, OAI-SearchBot, Claude-User, Claude-SearchBot, Perplexity-User, PerplexityBot (no robots.txt counts as allowed).
• We show blocks on GPTBot (OpenAI model training), not scored; ClaudeBot (Anthropic model training), not scored; Google-Extended (Gemini training and grounding), not scored in v1; CCBot (Common Crawl's open dataset), not scored: blocking them is the site's own call.
• Whether Google-Extended should be scored is a rubric v2 question, and we'll announce it before changing anything.
• Then we fetch your homepage as LeaderfileBot and check it returns 2xx after redirects, with no challenge page.

How we test this:

• We fetch your homepage and your docs page as LeaderfileBot, our own scanner, and check neither answers with a challenge page, or a 401 or 403 that a normal browser gets past.
• One blocked page is a fail; both caps your score at 39.
• Firewalls often let in crawlers they can verify, so ChatGPT or Claude may still get in where our scanner can't.

How we test this:

• We look for your docs page: the first homepage link to a docs., dev. or developer(s). subdomain of your domain, or to a /docs or /developer(s) path; with none, we try https://docs.<host>/ then https://<host>/docs.
• It passes if that page returns 200.
• Board companies use a docs URL we confirmed by hand.

How we test this:

• We read your homepage and your docs page and look for a pointer to an llms.txt: a link to it, a <link> tag, a Link header with rel="llms-txt" or an X-Llms-Txt header, or a line on the page naming /llms.txt.
• It passes when one points at an llms.txt that answers with markdown links.
• AFDocs checks the same (llms-txt-directive).

What our check kept, up to 60 lines or 6 KB

<?xml version="1.0" encoding="utf-8" ?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
    
        
            
                <url>
                    <loc>https://www.mailersend.com/about-us</loc>
                    <lastmod>2026-03-27</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.5</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/blog</loc>
                    <lastmod>2025-04-25</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.9</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/contact-us</loc>
                    <lastmod>2026-05-01</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.5</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/help</loc>
                    <lastmod>2024-02-07</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.5</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/legal</loc>
                    <lastmod>2025-07-22</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>1.0</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/report-abuse</loc>
                    <lastmod>2022-12-27</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.5</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/signup-fr</loc>
                    <lastmod>2025-10-21</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.9</priority>
                </url>
            
                <url>
                    <loc>https://www.mailersend.com/signup-pl</loc>
                    <lastmod>2025-10-21</lastmod>
                    <changefreq>weekly</changefreq>
                    <priority>0.9</priority>
                </url>

How we test this:

• We fetch the Sitemap: URL from robots.txt, else /sitemap.xml, and check it returns 200 with a <urlset> or <sitemapindex> root element.

How we test this:

• We count the visible words in the raw HTML (no JavaScript run) of your homepage and your docs page, and check each has at least 150.
• With no docs page found (AR-FIND-02), the homepage is judged alone.

How we test this:

• We read your docs page and up to 7 more docs pages (the ones we read for other checks, then links on your docs page).
• A page fails when it answers 401 or 403 to a normal browser too, redirects to a sign-in page, or is a sign-in form with little else on it.
• A redirect counts as a sign-in when it adds one: a sign-in path the page didn't have, a login subdomain, or an identity provider's site such as Okta's when the page was on another site.
• A sign-up page, one whose title or main heading says sign up or create an account, isn't a login.
• A refusal only to automated readers is our scanner being blocked, not a login.
• A login on your docs page caps your score at 39; across the pages, a share of 25% or less caps it at 39, 50% or less at 59.

How we test this:

• We fetch /leaderfile-check-404, a page that shouldn't exist, and check it returns 404 or 410 after redirects.
• Off the board, if that address refuses automated readers, we try /leaderfile-check-404.html.

What our check kept, up to 60 lines or 6 KB

# llms.txt for MailerSend.com
# Last updated: 2025-12-15
# Purpose: To enable large language models to accurately comprehend and articulate information about MailerSend.

## Website overview

Project name: MailerSend
Website: https://www.mailersend.com
Description: MailerSend is a modern transactional messaging service built for developers, SaaS platforms, and businesses. It combines a powerful RESTful API and SMTP relay with a user-friendly interface, collaboration tools, analytics, and advanced features like dynamic templates, inbound routing, split testing and webhooks.

---

## Key concepts

- Transactional email and SMS delivery at scale
- REST API and SMTP relay support
- Dynamic templates and personalization
- Webhooks and inbound email routing
- Role-based access and collaboration
- Comprehensive analytics and logs
- Developer-first tools with drag-and-drop support for teams

---

Primary audience: Developers, SaaS companies, e-commerce platforms, agencies, and technical teams managing transactional communication systems.

---

## Core content sections

# Homepage
https://www.mailersend.com/

# Product overview
https://www.mailersend.com/features/

# Pricing
https://www.mailersend.com/pricing
https://www.mailersend.com/pricing.md

# Blog
https://www.mailersend.com/blog

# About
https://www.mailersend.com/about-us

# Contact
https://www.mailersend.com/contact-us

---

## Features

- [Transactional Emails](https://www.mailersend.com/features/transactional-emails)  
  Send automated emails like receipts, alerts, and password resets using the API or SMTP.

- [Email API](https://www.mailersend.com/features/email-api)  
  Fast, secure RESTful API for sending emails at scale.

- [SMTP Relay](https://www.mailersend.com/features/smtp-relay)

How we test this:

• We read llms.txt at your site root and, if your docs live on another host, at your docs root, and check one returns 200, isn't HTML and has at least one markdown link.
• Off the board, we also try your docs. host and /docs/llms.txt.
• We read the first 2 MB: a larger file is judged on that part, and the result says "read the first 2 MB; the file is larger".

How we test this:

• We read the llms.txt AR-READ-07 passes on (the first with markdown links) and fetch up to 12 of its links, spread through the file, two at a time.
• A link is broken when it answers 404 or 410, or its host doesn't exist.
• A 2xx after redirects resolves, and so does an answer like 400, 405 or 406 that shows the address is there (an MCP endpoint answers a plain GET with 405).
• A refusal, a 429 or a server error isn't judged.
• The credit is the share that resolve, halved when the file runs to 50,000 characters or more, and nothing past 100,000: AFDocs' size bands.
• With no llms.txt it isn't counted: AR-READ-07 counts that.

How we test this:

• On each docs page we read (up to 7) we count the characters of visible text in the raw HTML, and of its Markdown copy if it has one, and judge the page by the larger of the two: an agent reading either may be cut off.
• Under 50,000 passes, up to 100,000 is half, more fails: AFDocs' bands, from the limits agents cut pages at.
• The credit is the average across the pages.

What our check kept, up to 60 lines or 6 KB

<meta name="description" content="Start sending emails with our top-rated service. Sign up for free now to streamline your email sending process with API or SMTP.">

How we test this:

• We check your homepage's raw HTML (no JavaScript run) has a non-empty meta description or og:description.

What our check kept, up to 60 lines or 6 KB

<h1>What is MailerSend?</h1>
<h2>MailerSend API</h2>
<h2>Base URL</h2>
<h2>Official libraries</h2>
<h3>On this page</h3>

How we test this:

• We check your docs page's raw HTML (no JavaScript run) has at least 2 headings (h1 to h3) with text and at least 150 visible words.
• Off the board, a docs page that comes back as markdown counts # to ### lines outside code blocks as its headings.

How we test this:

• On your docs surface, we look for a code block that carries a language tag: language-* or lang-* on <pre> or <code>, code-language-* on any element (a code block's wrapper, say), or a data-language or data-lang attribute.
• In markdown files, a fenced block with a language (```ts) counts.
• If no page shows one, we read the markdown copy each HTML page declares (a <link rel="alternate" type="text/markdown">, or its URL plus .md listed in your llms.txt), since many docs sites add the language label with JavaScript.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.

What our check kept, up to 60 lines or 6 KB

// Fallback to hardcoded rates this.eur_rate = '0.92'; this.gbp_rate = '0.79'; } } } }" x-init="initialize()" > How many emails do you plan to send? Free Special Pricing for - Use coupon code to get off. Pay monthly Pay yearly Save 10% USD EUR GBP Pricing in Euros and British Pounds is for informationa

How we test this:

• We fetch the first homepage link with 'pricing' in its path, else /pricing (board companies: a pricing URL we confirmed by hand), and check it returns 200 and its raw text (no JavaScript run) shows a price or 'free' within 80 characters of month, mo, year or yr.
• Off the board, a pricing address that answers with JSON counts when it has a price field.

What our check kept, up to 60 lines or 6 KB

---
description: Discover the power of MailerSend's API or seamless email communication. Get started today and take your messaging to the next level.
title: What is MailerSend? | MailerSend Developers
image: https://developers.mailersend.com/og/image.png
---

[![MailerSend](https://developers.mailersend.com/logo.svg)![MailerSend](https://developers.mailersend.com/logo-white.svg)](https://developers.mailersend.com/)

Search`⌘``K`

[Dashboard](https://app.mailersend.com/login) [Help](https://www.mailersend.com/help) [GitHub](https://github.com/mailersend/) [Status](https://status.mailersend.com/) [What is MailerSend?](https://developers.mailersend.com/) [General API resources](https://developers.mailersend.com/general) [Sending emails with MailerSend SDKs](https://developers.mailersend.com/sdk)

API Reference

Email API

Verification

SMS API

WhatsApp API

Account

Documentation

Guides

Tools

MCP Server

Ask AI

# What is MailerSend?

Discover the power of MailerSend's API or seamless email communication. Get started today and take your messaging to the next level.

Copy MarkdownOpen

MailerSend is a powerful transactional email system built for developers but designed so non-tech teams can contribute without coding.

We believe that creating, sending and tracking transactional emails is a team effort. Everyone can contribute to analyzing and optimizing email engagement with MailerSend's intuitive interface, combined with a powerful sending infrastructure to scale quickly.

At the moment, transactional emails can be sent through MailerSend’s Email API or using SMTP relay.

## MailerSend API

MailerSend API is RESTful, fully featured, and easy to integrate with.

## Base URL

All API requests should start with the following base part:

```
https://api.mailersend.com/v1/
```

## Official libraries

How we test this:

• On each docs page we read (up to 7), one Markdown answer with content passes the page: it answers Accept: text/markdown with text/markdown, declares a copy with <link rel="alternate" type="text/markdown"> that returns Markdown, or the address the page lands on, after redirects, ending in .md does (for one ending in a slash, both /page.md and /page/index.md).
• An empty answer doesn't count.
• The credit is the share of pages that pass.
• AFDocs, Cloudflare's isitagentready and is-agentic check it.

What our check kept, up to 60 lines or 6 KB

{
  "@context": "https://schema.org",
  "@graph": [
    {
      "@type": "Organization",
      "name": "MailerSend, Inc.",
      "url": "https://www.mailersend.com",
      "logo": "https://www.mailersend.com/images/logo.svg",
      "sameAs": [
        "https://www.facebook.com/MailerSend",
        "https://x.com/MailerSend",
        "https://www.linkedin.com/company/mailersend",
        "https://www.youtube.com/channel/UC_m5qoVCrqBTlPZ7Y5N3UaA"
      ],
      "description": "MailerSend is a transactional email and SMS service providing reliable solutions for businesses worldwide.",
      "keywords": "Transactional Email, SMS Service, Email APIs, Business Communication",
      "contactPoint": {
        "@type": "ContactPoint",
        "contactType": "Customer Support",
        "availableLanguage": "Multilingual",
        "hoursAvailable": {
          "@type": "OpeningHoursSpecification",
          "dayOfWeek": [
            "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday",
            "Sunday"
          ],
          "opens": "00:00",
          "closes": "23:59"
        }
      },
      "address": {
        "@type": "PostalAddress",
        "streetAddress": "228 Park Ave S PMB 54955",
        "addressLocality": "New York",
        "addressRegion": "NY",
        "postalCode": "10003-1502",
        "addressCountry": "US"
      },
      "foundingDate": "2020-10-29",
      "founders": [
        {
          "@type": "Person",
          "name": "Ignas Rubezius"
        }
      ],
      "parentOrganization": {
        "@type": "Organization",
        "name": "AB Vercom filialas Lietuvoje"
      },
      "areaServed": "Worldwide"
    },
    {
      "@type": "WebApplication",
      "name": "MailerSend",
      "applicationCategory": "BusinessApplication",

How we test this:

• We check your homepage's raw HTML has an application/ld+json block that parses as JSON and has @type or @context.

What our check kept, up to 60 lines or 6 KB

{
    "linkset": [
        {
            "anchor": "https://api.mailersend.com/v1/",
            "service-desc": [
                {
                    "href": "https://api.swaggerhub.com/apis/MailerSend/mailersend-api/1.0.0-oas3.1",
                    "type": "application/openapi+json",
                    "title": "MailerSend API OpenAPI specification"
                }
            ],
            "service-doc": [
                {
                    "href": "https://developers.mailersend.com",
                    "type": "text/html",
                    "title": "MailerSend API documentation"
                }
            ],
            "status": [
                {
                    "href": "https://status.mailersend.com",
                    "type": "text/html",
                    "title": "MailerSend status page"
                }
            ]
        }
    ]
}

How we test this:

• We fetch five standard .well-known files and check at least one returns 200 with valid JSON: oauth-authorization-server (RFC 8414), oauth-protected-resource (RFC 9728), openid-configuration, api-catalog (RFC 9727) and agent-card.json (A2A).
• This list is ours: AgentReady v2.0 doesn't name one.
• Off the board, on a miss, we also read oauth-protected-resource on the mcp., api. and docs. hosts of your domain, where that metadata usually lives, and it counts only with its resource field.

What our check kept, up to 60 lines or 6 KB

e Plus menu and select connectors. You may need to explore different prompting techniques to call the correct tools. Available Tools Email Management send_email : Send a single email with templates, personalization, and attachments send_bulk_email : Send multiple emails in a single request get_bulk_email_stat

How we test this:

• Passes when AR-ACT-03 passes (your docs surface names your own MCP server, not just a mention or a blog post about one; on the board, only an MCP server with a tool that acts on the product: send, manage or query, not only search docs, since AgentReady calls this "the interface an agent acts through"), or when your docs surface shows a CLI install: brew install, npm i -g, npm install -g, pipx install, uv tool install, go install, az extension add, or curl ... | sh (or | bash).
• A mention of MCP that isn't your own server, with no CLI install, isn't counted.
• For board companies, the CLI half counts only a command of the product's own CLI that we confirmed by hand, like az communication email send or twilio email:send, on the pages we read or on the docs page that shows it: an install alone could be any tool (an MCP setup guide installing pnpm, say).
• For a product inside a larger platform, the platform's MCP server or CLI counts when its docs show it covers the product.
• An MCP server earns both this check and AR-ACT-03, because AgentReady lists them as two items.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.

How we test this:

• We look for an OpenAPI or Swagger document: for board companies, a URL we confirmed by hand; then up to 2 links on your docs surface whose URL mentions openapi or swagger, or whose link text does for a .json or .yaml file (files on other sites count when your docs link them; an address written out in your llms.txt or another text file counts as a link, and its line as the link text); then /openapi.json and /openapi.yaml on your host and your docs host.
• Off the board, a .json or .yaml link under an llms.txt heading that names OpenAPI counts as a link to a spec, or, where that section has none, a link with no file extension, and on a miss we also try those two on the docs., developers. and api. hosts of your domain.
• It passes if one parses as JSON or YAML with an openapi or swagger key and at least one path.
• A spec over 10 MB counts as couldn't check.

What our check kept, up to 60 lines or 6 KB

npm install mailersend
pip install mailersend

How we test this:

• On your docs surface we look for an npm install (npm, yarn, pnpm or bun) and a pip install (pip, poetry or uv) of a named package.
• Both must appear, on any of the pages (AgentReady: npm and PyPI).
• Off the board, uv tool install and pipx install also count as a pip install.
• Off the board, if one is missing we also read the markdown copy each HTML page declares (a <link rel="alternate" type="text/markdown">, or its URL plus .md listed in your llms.txt), then up to 2 pages your llms.txt names for that language.
• AgentReady v2.0 asks for SDKs and a CLI here; this check tests the npm and PyPI half, and a CLI counts under AR-ACT-10.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.

What our check kept, up to 60 lines or 6 KB

ind all information about the endpoints’ authorizations, possible statuses of your emails, and validation errors. Authentication Authentication is done by adding an Authorization header containing an API token as a value to your API request. To do this, you need to add an Authorization header with the contents of the header being Bearer XXX where XXX is your API token. Authorization : Bearer XXX API tokens

How we test this:

• A stand-in: AgentReady asks for self-serve key generation with documented scopes, or OAuth metadata, and key sign-up can't be tested in code.
• It passes if OAuth metadata parses as JSON with the field its RFC requires (issuer for RFC 8414, resource for RFC 9728), or if your docs say "API key" or "API token" (also inside a placeholder like YOUR_API_KEY) within 200 characters of a documented auth header: an X-...-Key or X-...-Token header, a header named ...-Key or ...-Token, Authorization with Bearer, or "Bearer API key".
• The word "token" on its own doesn't count.
• For board companies we also read the authentication page their docs link.
• Off the board, OAuth metadata with its resource field on your mcp., api. or docs. host also counts.
• A board company whose API signs each request (like AWS Signature Version 4) or takes the key in the request body isn't counted: this stand-in can't judge that kind of auth either way.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.

How we test this:

• In the OpenAPI spec AR-ACT-02 finds, we count the operations with a non-empty operationId.
• The credit is the share that have one.
• With no spec, it isn't counted: AR-ACT-02 already counts that.

What our check kept, up to 60 lines or 6 KB

e Plus menu and select connectors. You may need to explore different prompting techniques to call the correct tools. Available Tools Email Management send_email : Send a single email with templates, personalization, and attachments send_bulk_email : Send multiple emails in a single request get_bulk_email_stat

How we test this:

• On your docs surface we look for your own MCP server and quote the line: your name next to "MCP" ("Acme MCP server"), "our" or "official" MCP server, or an mcp.<your domain> address.
• Any other mention of "MCP server" or "Model Context Protocol", like a directory or an explainer, isn't counted: it can't fail you and it earns no points, because we can't tell the server is yours.
• A mention in a link to a blog post, or on an llms.txt line that links to one, doesn't count at all: a post about building a server isn't one you ship.
• For board companies we read the MCP page their docs link and list the tools it documents: a server that only searches your docs counts here, as AgentReady describes an MCP server as a "standard tool protocol for docs search and actions".
• We don't probe /mcp or call any server.
• Off the board, OAuth metadata with its resource field on your mcp. host also counts: it's the server's own file.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.

How we test this:

• In the OpenAPI spec AR-ACT-02 finds, we count the operations that declare a 4xx, 5xx or default response with a schema, directly or through a $ref.
• The credit is the share that do.
• We note when they use application/problem+json (RFC 9457), the standard shape.
• With no spec, it isn't counted.
• The IETF's draft agent-friendly API profile, is-agentic and Alpic check it.

How we test this:

• We check your homepage's raw HTML, inline scripts included, contains modelContext (AgentReady names document.modelContext).
• External scripts aren't fetched.

How we test this:

• Any of three passes: /.well-known/agent-skills/index.json on your site or your docs (or one a Link header names) lists a skill whose file answers; your docs or llms.txt link a SKILL.md that answers with a name and a description; or your docs show a skills install command, on a page we read or on up to 3 pages your docs or llms.txt link about skills or your CLI.
• An install is npx skills add, claude plugin install, a git clone into a skills folder, or your own command line running plugin install or skills add right after the word skill.
• An index under a folder, like /developer/, may list its files from that folder.
• Cloudflare's isitagentready, agenticplug and Alpic check it.

What our check kept, up to 60 lines or 6 KB

{"issuer":"https://mcp.mailersend.com","authorization_endpoint":"https://mcp.mailersend.com/authorize","token_endpoint":"https://mcp.mailersend.com/token","registration_endpoint":"https://mcp.mailersend.com/register","response_types_supported":["code"],"response_modes_supported":["query"],"grant_types_supported":["authorization_code","refresh_token"],"token_endpoint_auth_methods_supported":["client_secret_basic","client_secret_post","none"],"revocation_endpoint":"https://mcp.mailersend.com/token","code_challenge_methods_supported":["S256"],"authorization_response_iss_parameter_supported":true,"client_id_metadata_document_supported":false}

How we test this:

• We look for OAuth authorization server metadata (RFC 8414): at /.well-known/oauth-authorization-server on your site, through the authorization_servers your protected-resource metadata (RFC 9728) names, and on your mcp. host.
• It passes when it lists S256 in code_challenge_methods_supported, has scopes_supported, and has a registration_endpoint or client_id_metadata_document_supported, as the MCP authorization spec asks.
• With no OAuth metadata, it isn't counted.

What our check kept, up to 60 lines or 6 KB

TypeScript/JavaScript: npm install mailersend
Python: pip install mailersend
Go: go get github.com/mailersend/mailersend-go
Java: < artifactId >java-sdk</ artifactId >

How we test this:

• On your docs surface we look for an install in each of four languages: TypeScript/JavaScript (npm, yarn, pnpm or bun), Python (pip, poetry or uv), Go (go get) and Java (a Maven <artifactId> or a Gradle implementation line).
• All four must appear.
• This shows how to install, not that a package is official.
• If none of the pages we read is a quickstart or SDK page, a miss isn't counted: it can't fail you or withhold your score.
• Ours, not AgentReady's.

How we test this:

• In the OpenAPI spec AR-ACT-02 found, we look for a POST operation on a path containing mail, email, message or send.
• No spec counts as a fail.
• Ours, not AgentReady's.

What our check kept, up to 60 lines or 6 KB

and white-label resellers sending at scale $ $1 ')"> /month € $1 ')"> /month £ $1 ')"> /month $ $1 ')"> /month € $1 ')">25 /month £ $1 ')">25 /month 50,000 emails /month 150 SMS /month Extra usage $ 1.30 € 1.20 £ 1.03 /1,000 emails Start free trial Try Professional features free for 14 days All in Starter, plus: 7-day

How we test this:

• On the pricing page AR-READ-11 reads, we look for "free" within 300 characters of a number followed by emails, messages or sends and a period (a month, a day, or 30 days), like "3,000 emails/month" or "4,000 sends in any rolling 30-day window", in the raw text (no JavaScript run).
• A one-time allowance with no period doesn't count.
• Ours, not AgentReady's.