darkzwarmer vs Folderly

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.

Folderly is a suite of AI and email deliverability tools for B2B teams. It combines campaign drafting with checks and monitoring intended to help assess email placement and sender reputation. Inbox Insights reviews inbox placement along with sending IP and domain signals before a campaign; its free plan includes 2 tests per month. Pulse tracks placement over time, and real-time alerts are available for free. Folderly AI turns an offer, audience, and goal into a campaign draft and directs users to relevant checks. Other tools cover DMARC reports, public DNS and IP inspection, email HTML previews, and real-message testing; DMARC is a pilot and Mirror is in beta. Folderly says it connects to email service providers through API and SMTP, supports custom providers, and names Amazon AWS, Sendpulse, Elastic Email, Google Workspace, SendGrid, and Microsoft Outlook. Product availability, access, and plans vary by product. Listed options include Inbox Insights Monthly at $79 a month for 100 tests and Inbox Insights Yearly at $799 a year for 100 tests per month. Folderly mailbox plans list a minimum commitment and per-mailbox monthly amounts, billed yearly.