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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.

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.

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

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.

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

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.

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

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

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.

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.

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.

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

It is an Email Tracking for Gmail and GSuite, adds the double check marks to your mail if it is read by recipient (Just like WhatsApp), Receives real-time pop-ups notification on your desktop when your emails are opened.

It is an advanced MTA built to handle the most critical reliability, performance, security, and deliverability requirements.