Free-tier email infrastructure

Abstract Email Validation API

Abstract API’s Email Validation and Verification API provides real-time email verification designed to help teams reduce bounce rates, clean signup forms, and improve the quality of inbound leads. It ...

AgentMail

AgentMail is an email inbox API for AI agents. It provides programmatic creation and management of email inboxes, threads, replies, attachments, realtime events, custom domains, semantic search, and data extraction through REST APIs, SDKs, webhooks, and MCP support.

UserCheck

UserCheck is an email validation API that checks addresses and domains for disposable mail providers, forwarding services, public email domains, role accounts, MX record validity, syntax errors, and c...

KwesForms

KwesForms is a form endpoint service for developers that accepts HTML form submissions, sends notification and autoresponder emails, and stores submission data for later management. The service works ...

Verimail is an email address verification service that checks bulk lists and individual addresses through a REST API. It removes syntax errors, duplicates, invalid domains, disposable addresses, catch...

Postmark

Postmark is an email delivery service that exposes both an Email API and SMTP service for sending transactional and broadcast email. The platform also includes inbound email processing, message streams, templates, webhooks, analytics, and official SDKs for common languages and frameworks.

EmailGuard API

EmailGuard API is an email validation service that checks addresses against live DNS and MX records, identifies disposable and role-based emails, and returns typo suggestions such as gmil.com to gmail.com. It is exposed as an API and can be used from a React component or backend form flow.

MailChannels

MailChannels provides email infrastructure for hosting providers, platforms, and developers through outbound filtering, inbound filtering, and an Email API. The service supports SMTP relay, REST API a...

emailvalidation.io is an email validation and email finding service. It validates single addresses or uploaded lists in realtime, and it also exposes a REST API for form validation and bulk processing.

Mailtrap

Mailtrap is an email delivery platform with two main products: Email API/SMTP for sending transactional and promotional email, and Email Sandbox for testing emails in staging, dev, and QA environments...

MailerSend

MailerSend is an email sending service that provides an email API, SMTP relay, dynamic email templates, inbound email routing, email verification, user management, multiple domains, DMARC monitoring, ...

Amazon SES

Amazon Simple Email Service (Amazon SES) is a cloud-based email service provider for sending and receiving email at scale. It is designed for transactional messages, marketing campaigns, newsletters, ...