darkzwarmer vs Warmerly

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.

Warmerly automates email warmup and checks deliverability for connected mailboxes. Its warmup feature sends threaded conversations with quoted replies and natural delays, and can recover warmup messages that end up in spam. InboxPulse checks SPF, DKIM, DMARC, MX and TLS daily. Google Workspace and Microsoft 365 connect through OAuth; other providers can connect over IMAP and SMTP, including Zoho and Namecheap Private Email. The service also lists LinkedIn warmup and outreach, plus WhatsApp messaging; LinkedIn costs $50/month per account separately. Plans include a free option with 100 campaign emails per month, and paid plans from $19/mo with a 7-day trial. Paid plans state that email sending is unlimited and unmetered. Warmerly runs on Android and the web, and offers an API. The operator says mailbox credentials and OAuth refresh tokens are encrypted at rest with AES-256-GCM, requests use TLS 1.2 or higher, and hosting and backups are in the European Union. The site names agencies, sales teams, telecom companies, lead-generation businesses, founders, SDRs and recruiters as users.