Best Open Source Email Marketing Tools in 2026

Mailchimp costs $13-350/month depending on subscribers. ConvertKit starts at $15/month. Here are the best open source alternatives for newsletters, email campaigns, and marketing automation.

Quick Comparison

Tool	Best For	License	Language	Self-Host
Listmonk	Newsletters	AGPL-3.0	Go	Docker
Mautic	Marketing automation	GPL-3.0	PHP	Docker
Mailtrain	Newsletter campaigns	GPL-3.0	Node.js	Docker
Postal	Transactional email	MIT	Ruby	Docker
Keila	Simple newsletters	AGPL-3.0	Elixir	Docker

Detailed Breakdown

Listmonk — Best Performance

Single Go binary, 50 MB RAM
100K+ emails per hour
Subscriber management with tags
Campaign templates (Go templates)
Analytics (open rate, click rate)
REST API
Double opt-in support
Bounce handling

Best for: High-volume newsletters with minimal server resources.

Mautic — Best Marketing Automation

Email campaigns + landing pages
Contact scoring and segments
Multi-channel (email, SMS, social, web push)
Drag-and-drop email builder
A/B testing
Dynamic content
CRM integration
Marketing automation workflows

Best for: Full marketing automation replacing HubSpot Marketing Hub.

Mailtrain — Best UI

Clean web interface
Template editor
List segmentation
Automation triggers
GPG encryption support
RSS campaigns
Multiple SMTP providers

Best for: Teams who want a Mailchimp-like UI for self-hosted newsletters.

Choosing the Right Tool

Need	Choose
Simple newsletters (fast)	Listmonk
Marketing automation	Mautic
Mailchimp-like UI	Mailtrain or Keila
Transactional email server	Postal
Minimum resources	Listmonk (50 MB RAM)

Cost Comparison (50K subscribers)

Tool	Software	SMTP (SES)	Total/month
Mailchimp	$299/month	Included	$299
Listmonk	Free	~$5	$10 (VPS + SES)
Mautic	Free	~$5	$15 (VPS + SES)

Annual savings with Listmonk: $3,468 vs Mailchimp Standard.

Compare all email marketing tools on OSSAlt — features, deliverability, and pricing side by side.