darkzwarmer vs Swokei Email Warmup

darkzwarmer is an open-source email warmup tool for domains and mailboxes the user owns and controls. It generates inboxes across those domains, exchanges warmup mail only between different domains, and replies to its own network’s messages after random delays of 30 minutes to four hours; messages from outsiders are ignored. Per-inbox volume rises from 5 to 35 messages daily over 28 days, then stays at the chosen steady-state level. Sends are randomized across a default 07:00–19:00 local window, with 2–8 minutes of jitter between consecutive sends; weekends pause. Outbound mail uses configurable SMTP, with Amazon SES, SMTP.com, Postmark, Mailgun, Brevo and SendGrid listed as examples. Inbound mail can use IMAP or Resend. The Python 3.11+ runtime stores state in SQLite and is designed to resume after crashes or reboots while preventing duplicate replies. It requires an always-on machine, at least two user-owned domains, SMTP service and an inbound-mail route. Windows scripts support unattended operation; Linux and macOS users can run it under a process manager or terminal session. Configuration includes inbox counts, timing, volume limits and optional scheduled inbox cohorts. The project is MIT-licensed and provided without warranty.

Swokei Email Warmup is a web-based outreach service for web design agencies and freelancers. It examines prospects’ websites in a headless browser, captures screenshots, and assesses design, copy, performance, and conversion paths. It can use those findings to write personalized outreach emails and send them from the user’s mailbox. Leads can be imported from spreadsheets, pasted rows, Google Sheets, a website URL, or a saved library. Positive replies can become deals in the built-in CRM, which supports pipeline stages, tasks, notes, files, and deal values. Mailbox warmup is included on every plan, with an automatic 30-day ramp and per-mailbox health and bounce-risk indicators. Swokei supports Gmail, Outlook, Yahoo, custom domains, and SMTP connections; for Gmail, it says it monitors only messages it sent. The Free plan costs nothing and starts with 20 credits, but has no mailboxes and does not allow sending. Paid plans start at $42/mo billed annually. The listed daily email limit is 50, and the warmup network is shared.