Open Source Email Infrastructure & Marketing Tools
Open source email servers and marketing tools you can self-host. Compare Mailchimp, SendGrid, and Postfix alternatives by deliverability. Updated Sept 2026.
MailCheap
MailCheap is an open-source newsletter app for writing, sending, and publishing email campaigns, from the dashboard or an AI agent via its built-in MCP server. Self-host it with your own Amazon SES or PostShiba account, or use MailCheap Cloud, which runs the same code. It imports lists from Beehiiv, Substack, and Mailchimp, gives every newsletter its own website, and bakes in deliverability protections like warm-up sending, list cleanup, and Gmail spam-rate monitoring.
listmonk
An open-source, self-hosted newsletter and mailing-list manager, and an alternative to Mailchimp and Sendinblue. listmonk ships as a single Go binary with a modern dashboard, scales to millions of subscribers, and supports SQL-based segmentation, templating, multi-list campaigns, and delivery through any SMTP provider.