Open source Mailchimp alternative

There are roughly 15-25 serious open source email marketing platforms competing in this space, with names like Mautic, OpenEMM, and Listmonk gaining traction. The core pain points are Mailchimp's opaque pricing, feature creep that buries what most SMBs actually need, and lack of data ownership—founders are sick of their subscriber lists living in someone else's black box. The real gap isn't in email-sending infrastructure (that's solved) but in the friction between setup, self-hosting, and long-term maintenance. A new entrant should obsess over three things: (1) a genuinely frictionless self-hosting experience (Docker, one-click deploys, clear docs), (2) a clean, modern UI that doesn't feel like software from 2008, and (3) transparent, straightforward automation workflows that don't require a PhD in email marketing. Most existing open source alternatives sacrifice UX for flexibility or require serious DevOps skills to run, which locks out solopreneurs and small teams. The window is open because there's a widening cohort of makers who prefer to own their tools entirely rather than rent them from platforms that treat them as data sources.