Open-source alternatives to Twilio SendGrid

1

Novu

Notification infrastructure for developers.

Team ChatDocker

40k

Stands out for the most GitHub stars. Novu has 40,202 GitHub stars, uses the MIT license, ships a Docker image and had 2,453 commits in the last year.

2

Listmonk

High performance, self-hosted newsletter and mailing list manager with a modern dashboard.

Newsletters & Mailing ListsDocker

24k

Stands out for the most recent release (v7.0.0-beta.1, October 2026). Listmonk has 23,972 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 460 commits in the last year.

3

Postal

Complete and fully featured mail server for use by websites & web servers.

Email ServersDocker

17k

Stands out for a permissive MIT license. Postal has 16,893 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year.

4

Stalwart Mail Server

All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.

Email ServersDocker

15k

Stands out for its Rust codebase. Stalwart Mail Server has 15,298 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 715 commits in the last year.

5

Maddy Mail Server

All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon.

Email Servers

6.1k

Stands out for the longest track record (since 2016). Maddy Mail Server has 6,115 GitHub stars, uses the GPL-3.0 license and had 90 commits in the last year.

6

Haraka

Fast, highly extensible, and event driven SMTP server.

Email Servers

5.6k

Haraka has 5,627 GitHub stars, uses the MIT license and had 90 commits in the last year.