Email tools directory

Every developer email tool, in one place.

A curated, honest directory of the email-tooling ecosystem — platforms, inbound & parsing, agent & MCP email, SMTP relay, deliverability, testing, open-source servers, and automation.

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Email platforms

Full-stack developer email APIs for sending and receiving.

24 tools

MailKite

Ours

Receive email as a webhook, send with one API. Unlimited free domains.

Free tier + usage-based View

Resend

Polished send API with a React-first SDK; inbound added more recently.

Free tier + usage-based View

Postmark

Battle-tested transactional send + inbound parse, known for deliverability.

Usage-based, tiered View

SendGrid

Deliverability heavyweight for outbound at scale; inbound parse is secondary.

Volume-tiered plans View

Amazon SES

Lowest per-email price; inbound needs receipt rules + S3 + SNS + Lambda.

Pay-as-you-go per message View

Mailgun

Flexible inbound Routes via a regex rule engine; sending-first platform.

Volume-tiered plans View

MailerSend

Transactional + SMS API; inbound routing; sibling to MailerLite.

Free tier + usage-based View

Brevo

Multi-channel suite (email/SMS/WhatsApp) + transactional API; formerly Sendinblue.

Free tier (300/day) + tiered View

Mailjet

Send API + MJML templating + collaboration; inbound Parse API. Owned by Sinch.

Free tier (200/day) + tiered View

SparkPost (Bird)

Enterprise delivery + analytics; brand dissolved into Bird.

Bird pricing (usage-based) View

Elastic Email

Low-cost email API + marketing; reseller/white-label; MCP server.

Free tier + contact-based tiers View

SocketLabs

Delivery + Spotlight analytics/routing across multiple providers.

Tiered + custom View

ZeptoMail

Transactional-only; Zoho-backed; credit-based pricing.

Credit-based (~$0.10–0.18/1k) View

Loops

Contact-based pricing; transactional + broadcast in one; for SaaS.

Free tier (1k contacts) + contact tiers View

Plunk

Open-source (AGPL); transactional + marketing + automation; self-host.

Open source (self-host) + managed cloud View

MailPace

Transactional-only; EU-hosted; no tracking; idempotency keys.

Usage-based (from ~$4/mo) View

Mandrill (Mailchimp)

Mailchimp's transactional add-on; API + SMTP + inbound parsing.

Add-on (requires Mailchimp account) View

Sendy

Self-hosted; one-time license; sends via SES for ~$1/10k.

One-time license ($69) View

Listmonk

OSS (AGPL); single Go binary; extreme throughput; multi-SMTP queues.

Open source (self-host) View

Mautic

OSS (GPL); marketing automation + CRM; the self-hosted HubSpot.

Open source (self-host) + managed hosting View

MailerLite

Marketing email + landing pages + MCP server; EU-resident.

Free tier + paid tiers View

Kit (ConvertKit)

Creator-focused; paid newsletters + commerce; Kit MCP.

Free (10k subs) + creator tiers View

Customer.io

Lifecycle/behavioral; email/SMS/push/in-app; Liquid templating; dev SDKs.

Free trial + usage-based View

Klaviyo

Ecommerce CRM + email/SMS; Shopify-centric; built-in CDP.

Free tier (250 contacts) + contact tiers View

ActiveCampaign

Marketing automation + CRM; best automation builder; owns Postmark.

Tiered by contacts View

Inbound & parsing

Email-to-webhook, email-to-JSON, and parsing services.

4 tools

Agent & MCP email

Inboxes, SDKs, and MCP servers that give AI agents email.

5 tools

SMTP relay

Send-only SMTP relay services for apps that speak SMTP.

3 tools

Deliverability & DNS

SPF/DKIM/DMARC tools, inbox testing, and monitoring.

9 tools

Email testing

Sandbox inboxes, preview, and spam-score checks for QA.

7 tools

Email clients & webmail

Apps and open-source UIs for reading and sending mail.

5 tools

Open-source mail servers

Self-hosted mail infrastructure you run yourself.

9 tools

Automation & routing

Workflow tools that route and act on email.

4 tools
Frequently asked

Email tools, explained

What is an email API?

An email API lets your application send, receive, or manage email programmatically over HTTP rather than SMTP. Developer email platforms like MailKite, Resend, Postmark, and SendGrid expose REST APIs (and SDKs) so you can send transactional mail, receive inbound email as webhooks, and handle delivery, bounces, and authentication (SPF/DKIM/DMARC) from code.

Which email service is best for developers?

It depends on the job. For inbound email as webhooks, look at MailKite, CloudMailin, or Mailparser. For transactional sending, Resend, Postmark, and SendGrid are popular. For AI agent inboxes, MailKite MCP and AgentMail are purpose-built. The best choice is the one that matches your direction: send-only, receive-only, or both on one platform.

What's the best tool for inbound email?

For receiving email as a webhook/JSON, the main options are MailKite (parsed JSON with threading and auth verdicts), CloudMailin (HTTP POST), SendGrid Inbound Parse (multipart), and Mailparser (no-code visual parsing). MailKite is the most developer-friendly for clean JSON payloads and also handles sending.

How do I give an AI agent an email inbox?

Use an MCP email server or an email API built for agents. MailKite MCP is a hosted remote MCP server (OAuth, no install) that gives any MCP-compatible agent (Claude, Cursor, ChatGPT Apps) a real email inbox to send, receive, and reply. AgentMail and the Gmail/Microsoft Graph APIs are alternatives that operate on existing or new mailboxes.

Are these tools free?

Most have a free tier. MailKite, Resend, Brevo, and MailerSend offer free plans for low volume. Open-source servers like Mailcow, Stalwart, and Postal are free to self-host but cost you operational time. Check each tool's pricing model on its page — this directory stores models, not tier numbers, because pricing changes.

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