darkzwarmer

Windows · Mac · Linux · Self-hosted

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Freedom report

Two barsScore 5.5

Free tierNo free tier on record
Open codeNo open-source code on record
Runs widely3 of 6 device platforms
DocumentedPlans, terms and facts published

darkzwarmer is ranked #5 of 24 in email warmup software on Freedom251. It runs on Linux, macOS, Self-hosted, Windows.

Compared on email warmup software

Warmup network: private
Mailbox providers: smtp
Custom warmup schedule: Yes
Multiple mailboxes: Yes

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The record

Purpose: darkzwarmer generates inboxes across user-provided domains, sends warmup email between those inboxes, and replies after human-like delays.
Warmup schedule: Per-inbox sending volume ramps from 5 to 35 messages per day over 28 days, then stays at the steady-state volume.
Cross-domain traffic: Each inbox sends only to inboxes on other domains, and the tool does not use same-domain pairs.
Replies: The network waits a random 30 minutes to 4 hours before replying in-thread to its own messages, and ignores outsider mail.
Sending integrations: Outbound delivery uses configurable SMTP and the README lists Amazon SES, SMTP.com, Postmark, Mailgun, Brevo, and SendGrid as examples.
Inbound integrations: Inbound mail can be received through IMAP or Resend; the Resend setup uses a Vercel webhook and an Upstash Redis queue.
Self-hosting: The project describes itself as a Python runtime backed by SQLite that users run on an always-on machine or VPS.
Requirements: It requires Python 3.11 or later, at least two user-owned domains for cross-domain traffic, an outbound SMTP provider, and a way to receive mail.
Controls: Configuration includes inbox counts, sending windows, send delays, reply delays, steady-state volume, and an optional per-inbox daily send ceiling.
State and recovery: SQLite stores runtime state, and the README says the tool resumes after crashes or reboots and prevents duplicate replies with a unique index.
Security practices: The Resend webhook verifies request signatures, while SMTP, Resend, Upstash, and IMAP credentials are configured locally and credential files are gitignored.
Responsible use: The maker says the tool only emails its own network and is intended for domains and mailboxes the user owns and controls.
Operating system support: The README provides unattended-operation scripts for Windows and says Linux and macOS users can run the process under a service manager or terminal session.
License and warranty: The project is MIT-licensed and provided as-is without warranty.

Where it ranks on Freedom251

Best Email Warmup Software in 2026#5 of 24

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Sources

github.com/darkzOGx/darkzwarmer· checked 7 Oct 2026