BillionMail
Leading#4 in Open sourcemedium confidence
A self-hosted mail server plus marketing/newsletter stack (~15.4k stars) for sending on your own domain and IP at scale. Sending infrastructure and deliverability, not cold sequencing or copy.Our read
Why it ranks #4
A fast-growing self-hosted mail-server and marketing project at roughly 15k GitHub stars, notable for bundling infrastructure and campaigns but still young relative to mature mail stacks.Here is the catch
operating a mail server carries significant security and deliverability work
not purpose-built for personalized cold sequences
you own IP reputation, abuse handling and compliance
Does this well
combines mail infrastructure and campaign tooling
avoids per-contact SaaS pricing
active project with strong early adoption
Pricing
Checked by hand on 2026-07-23. Prices in this category change often — if this looks wrong, it probably is.
Key features
self-hosted mail servernewsletter and campaign sendingdomain and reputation monitoringtemplates and delivery analytics
Sources we read
Quick facts
More in this area
The rest of the Open source column.- 1MauticThe recognized open-source marketing-automation platform (~10.2k stars); its campaign/drip builder drives multi-step email sequences. Built for nurture more than pure cold prospecting, so it is adapted for outreach rather than cold-native.
- 2OpenOutreachA purpose-built self-hosted AI cold-outreach agent (~2.5k stars) that finds ICP leads, resolves work emails and sends personalized outreach from your own mailbox. The closest OSS fit for an end-to-end cold pipeline, but younger and smaller than the platforms above.
- 3listmonkThe highest-star self-hosted bulk email / campaign sender (~22.4k stars). Newsletter and opt-in oriented rather than cold-native, so it is a strong sending backend but not a sequencing or copywriting tool — hence medium for cold outreach.
- 5artbyjazi/cold-outreach-builderA skill file that has an AI assistant interview you, then generate your own local Python and Streamlit sending tool.
- 6dancolta/trustpilot-outreach-automationScrapes one- and two-star Trustpilot reviews of competitors and drafts emails quoting them in Gmail, leaving every send for you.
- 7Webeasetech/densheesSelf-hosted outreach platform that sends from your own inboxes and drives campaigns, leads and CRM through typed natural-language commands rather than menus.