Transactional Email Infrastructure

Ark is the AI first email API. Send transactional emails with native MCP support, sub-second delivery, and 99.9% deliverability.

Don't stress over Amazon SES or get banned by SendGrid. Transmit gives you Postmark-level happiness with the power of AWS. Start sending in minutes.

Twilio SendGrid's cloud-based email infrastructure relieves businesses of the cost and complexity of maintaining custom email systems. Twilio SendGrid provides reliable delivery, scalability & real-time analytics along with flexible API's.

Amazon SES eliminates the complexity and expense of building an in-house email solution or licensing, installing, and operating a third-party email service. The service integrates with other AWS services, making it easy to send emails from applications being hosted on services such as Amazon EC2.

Mailgun is a set of powerful APIs that allow you to send, receive, track and store email effortlessly.

Mandrill is a new way for apps to send transactional email. It runs on the delivery infrastructure that powers MailChimp.

It is a single module with zero dependencies – code is easily auditable. The email delivery is Secure using TLS/STARTTLS. You can use HTML content, as well as plain text alternative.

Postmark removes the headaches of delivering and parsing email for webapps with minimal setup time and zero maintenance.

Mailjet is a real-time Cloud Emailing platform: scalable, agile and flexible. Our unique algorithm boosts your deliverability and our platform provides in-depth insight so you can optimize more than ever.

It is a free and open-source mail transfer agent that routes and delivers electronic mail. It is Wietse Venema's mail server that started life at IBM research as an alternative to the widely-used Sendmail program. Now at Google, Wietse continues to support it.

SparkPost is the world’s #1 email delivery provider. We empower companies with actionable, real-time data to send relevant email to their customers which increases engagement and both top and bottom line revenue.

We offer one platform that covers all email-related needs in one place: testing, sending, and in-depth tracking to control how email infrastructure works and performs.

It is a modern email sending platform focused on providing the best developer experience. Build, test, and deliver transactional emails at scale.

Send email from your app with a simple API call, Sendwithus manages the rest. Templates, testing, data management, segments, and analytics are all accessible through a friendly dashboard.

It is an open source IMAP and POP3 email server for Linux/UNIX-like systems, written with security primarily in mind. It is an excellent choice for both small and large installations. It's fast, simple to set up, requires no special administration and it uses very little memory.

It adds scheduled sending and the easiest, most integrated email reminders to Gmail, helping you reach Inbox Zero.

A new kind of transactional email service designed for developers to work faster and smarter with a powerful infrastructure to scale quickly.

It is a premium email delivery and email relay solution that enables you to send and track high volume emails effortlessly. Integrate and start sending in minutes.

Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready for you to run on your own servers. Postal was developed by aTech Media to serve its own mail processing requirements and we have since decided that it should be released as an open source project for the community.

250ok is an email deliverability tools company that produces a Software‐as‐a‐Service (“SaaS”) platform to monitor and measure the deliverability of email networks. These networks consist of companies sending various forms of messages including marketing, transactional, share, and others from various platforms.

It is an email delivery service for your transactional and marketing emails. It replaces your email infrastructure so you don’t have to build, scale, and maintain these systems in-house. With an easy SMTP service you can start quickly, while our robust API gives you full control over email processing and reporting. Your transactional emails are delivered instantly and your marketing campaigns can be scaled to millions.

It helps build lasting business relationships, right from your inbox. A sales engagement platform designed for sales professionals and account managers.

Transactional emails are the forgotten step child of internet marketers. Apostle.io empowers marketers to manage transactional emails themselves, as they would their list based campaigns. Preview, Update, Analyse and Test your transactional email all in one place.

It is the speedy transactional email delivery service that provides reliable Inboxing in less than a second, all with a very disruptive pricing model. Only pay for unopened emails.

CloudMailin allows you to receive any volume of incoming email via a Webhook. You are given an email address that will forward any incoming message to your app, as an HTTP POST, within milliseconds. You can also seamlessly check the delivery status of each of your incoming emails via the dashboard, bounce emails that you do not wish to receive and use your own domain name.

Is an AI-driven multichannel outreach platform that reaches prospects where they're most active while keeping every message personal, timely, and effective.

It is an all-in-one tool for email deliverability to make your Email Channel Reliable. It raises your sender reputation by interacting with real people in any language and helps you to hit the inbox of your prospect. Full automation.

Your transactional email should NOT trigger spam or marketing filters. Flute Mail plugs into your existing API provider to properly isolate segments, boost inbox rates, and safely store your transactional email data.

Pinpoint email issues before you hit "send". Secure your emails from malicious actors and ensure your email delivery to the inbox.

Free email verifier & checker to validate email addresses instantly. Reduce bounces and verify emails in real time.

Free email checker and email verification with 99.9% accuracy. Reduce bounces, protect sender reputation. 100 free email verification credits daily.

Sidemail is an all-in-one email delivery platform for startups that makes sending emails simple. It has everything for delivering and managing emails – email API, transactional emails, email marketing and automation, contact management, no-code email editor, email templates, subscribe forms, and more. Perfect for teams & developers that want reliable deliverability without the bloat. We're based in the EU and GDPR compliant.

It offers a simple REST-based JSON API enabling you to thoroughly check and verify email addresses right at the point of entry into your system.

It helps new brands and startups build an audience while they focus on building a product

It is an easy way to manage your outgoing emails from your apps. From creating and sending your emails to monitoring and managing their stats, you can do really useful things with it without worried about time zone disaverage.

It is a fully self developed solution, truly innovative in several respects, particularly scalable and configurable. This messaging solution offers the entire range of mail services — SMTP, POP3, IMAP, WebMail (Desktop and Mobile versions) — includes List server, Logging, Reporting, and FTP Backup modules and provides various, flexible administration options (including a central Web administration interface — WebAdmin).

It is a self-hosted open-source application that provides a REST interface on top of any email account you have access to read and send emails. Combining these features would give you a similar email sending experience you'd get from a transactional email service.

The world's most reliable inbox architecture for cold email teams sending 100k+ monthly. Zero configuration. Total deliverability control.

Use AI to find prospects that need you, automatically craft personalized cold emails for each, and scale effortlessly

Aepto is an AI-powered domain monitoring platform built to give full visibility and control over domains spread across multiple providers. Instead of logging into separate registrar, hosting, and email dashboards, Aepto centralizes everything into one clean interface and continuously monitors domain health using public signals and AI analysis. Once a domain is added, Aepto automatically scans the registrar, hosting setup, email configuration, pricing, and renewal details—no APIs or integrations required. It monitors email deliverability, DNS records, website and subdomain uptime, content changes, and suspicious activity such as nameserver changes or lock status updates. When something goes wrong, Aepto alerts you early and clearly explains what happened and which provider to contact. Aepto also helps track domain expenses, visualize spending, assign ROI, organize domains into folders, and customize pricing and provider details when needed. Advanced features include AI-powered domain discovery, domain watch for tracking expiring domains you don’t own, distributed uptime monitoring, and customizable white-labeled status pages with incidents and maintenance updates. Designed for businesses, agencies, and teams that rely on domains for live websites, email, and APIs, Aepto focuses on proactive monitoring and clarity—so nothing breaks silently and small issues don’t turn into bigger problems.

Outreach Box is an AI-powered sales engagement, marketing automation and email outreach platform designed to help businesses find warm leads, scale outreach campaigns, and close more deals. With intelligent automation, unlimited email outreach, advanced deliverability, AI-generated personalized solution, and real-time campaign analytics, Outreach Box enables sales and marketing teams, agencies, and marketers to increase business reach and automate daily works for better output.

Email Deliverability Solutions (Analytics + Managed Services). We’ve helped 16,000+ companies like TikTok & HSBC land over 30B emails in customer inboxes.

A complete suite of deliverability tools & services makes it easy to get back in the inbox.

Postigo is an advanced email delivery and outreach platform designed to solve the technical challenges of cold email routing and sender reputation management. For growth engineers, marketing ops, and sales operations teams, maintaining high deliverability while scaling outbound campaigns often requires complex IP warming and constant monitoring of spam trap triggers. Postigo abstracts this complexity by providing out-of-the-box, fully warmed-up SMTP servers paired with an AI-driven content generation engine. By dynamically generating unique, personalized email payloads at scale, Postigo prevents campaigns from being flagged by algorithmic spam filters that detect repetitive content. With an emphasis on reliability and compliance, Postigo fits seamlessly into modern sales and marketing stacks, allowing teams to focus on campaign logic rather than underlying email infrastructure.

Free email deliverability checker for B2B outreach. Validate email addresses instantly, check MX records, detect role-based emails, and improve inbox placement before your cold email campaigns.

Mailwarm is an automated email warmup and deliverability platform designed to help businesses keep their emails out of spam folders and consistently reach the inbox.

Protect your domain with Dmarclytics. Run free DMARC, SPF, and DKIM checks to stop spoofing, enhance email authentication, and improve deliverability with powerful monitoring tools.

Dyspatch is an industry leading email production platform. Build engaging, interactive email templates in minutes, and collaborate with key stakeholders all within Dyspatch. Easily integrate with your existing email service providers.

Mailit is a drop-in microservice for sending emails over a REST API.

It is an open source tool for developers to set up customer notifications in less than 5 minutes. Just connect your database, set up event triggers, create content and connect to the service provider of your choice through DIY dashboard.