Best 6 Open Source SMTP.com Alternatives in 2026
Last Updated: February 1, 2026
SMTP.com is an email delivery platform that sends your business emails through their servers instead of your own. This means better delivery rates because they maintain good relationships with email providers and follow all the technical rules needed for emails to land in inboxes.
The service handles transactional emails, which are automatic messages sent when someone takes an action on your website or app. Examples include welcome emails, purchase receipts, shipping updates, and account notifications.
The best alternative to SMTP.com is 
Listmonk
ListmonkFree Self-Hosted Newsletter Platform. 
useSend
useSendOpen Source Email Platform for Developers and 
Plunk
PlunkOpen-Source Email Platform for Developers are also among the best options for Transactional Email Sending.
So, here are the 6 best alternatives to SMTP.com:
Listmonk is an email marketing platform that you install and run on your own server. Unlike cloud services such as Mailchimp, you download and host it yourself, which means you own all your data and pay no monthly fees.
It lets you manage subscriber lists, create email campaigns, and track performance through a clean web dashboard. The software is built using Go programming language and uses PostgreSQL as its database, making it fast and reliable.
You can send bulk newsletters, automated transactional emails, and even SMS messages through external services. The platform includes a drag-and-drop email builder, multiple template options, and detailed analytics. Because it is open source under the AGPLv3 license, developers can modify and customize it to fit specific needs.
useSend is a complete email platform that handles both business emails and marketing campaigns. Unlike regular email services, you only pay for emails you actually send. The platform includes a visual editor that looks like Notion, making it easy to design beautiful emails without writing code. It works through both a simple web connection and direct programming tools.
The service tracks your email results in real time, showing you who opened your emails and clicked your links. You can manage your contact lists, create email templates, and set up automatic bounce handling. Since it's open source, you can see all the code and even run it on your own servers if you want complete control. The platform also includes protection features to keep your sender reputation safe.
Plunk is a complete email platform that helps you send three main types of emails from one place. First, there are transactional emails - the automatic messages your app sends like password resets or order confirmations. Second, marketing automations - email sequences that trigger based on what your users do. Third, broadcast campaigns - newsletters and updates you send to many people at once.
The platform is open-source, which means the code is public and you can even host it yourself if you want. It runs on Amazon's email service, which makes it reliable and fast. Plunk offers a clean dashboard where you can create emails, track who opens them, and manage your contact list all in one spot.
DoubleZero is a self-hosted email platform built to work with Amazon Web Services Simple Email Service. Instead of paying monthly fees to companies like SendGrid or Mailchimp, you install this software yourself and connect it to your own AWS account. This gives you full control over your email sending at a much lower cost.
The tool provides a clean dashboard where you can send emails, track delivery status, monitor bounces, and view recipient activity. It connects to AWS SES through a simple setup process using SST configuration. You get all the features you need for transactional emails, like password resets and notifications, plus marketing features in the Pro version. The software runs in a Docker container, making it easy to deploy anywhere.
SendPortal is an open-source email marketing application that you host on your own server. Unlike paid services that charge per subscriber or per email, SendPortal is completely free to download and use. You just pay for your own hosting and the email sending service you choose.
The platform includes all the features you need to run email campaigns: subscriber lists, custom templates, message tracking, and detailed reports. It can handle multiple workspaces, making it useful for agencies managing different clients. SendPortal connects to major email providers through APIs, which means you get professional email delivery at wholesale prices.
Because it is self-hosted, you maintain complete control over your data and can customize the platform to fit your exact needs.
SENDUNE is a tool that connects to your Amazon Web Services account to send emails and text messages. You can send marketing emails to customers, important business messages like password resets, and text messages all from one place.
The platform includes a drag-and-drop email builder that lets you create good-looking emails without writing code. You can also use their HTML editor if you prefer coding your own designs, or keep things simple with plain text emails.
SENDUNE handles contact lists, email templates, and message tracking. It also includes automation features that send messages based on customer actions, like welcoming new signups or following up on purchases. The platform connects directly to your AWS account, which keeps costs low while maintaining high delivery rates.