The Deliverability Ledger · Cold Email · 1 post
Cold email that reaches the inbox
Getting cold outreach into the inbox without burning the domain it is sent from.
Other topics
- DeliverabilityThe signals inbox providers weigh, what each SMTP code and bounce type means, list hygiene, warm-up, and the numbers to measure yourself against.
- MicrosoftThe 550 and 421 errors Microsoft returns, how Exchange Online Protection scores a message, SNDS and JMRP, and how to get off the Outlook blocklist.
- GoogleThe Gmail bounces senders hit most (421 4.7.0, 421 4.7.28, 550 5.7.26), the bulk sender requirements, Postmaster Tools, and the way back out of the spam folder.
- BlacklistsHow to tell if you are listed, why IP and domain blacklists catch different things, and what SURBL listings mean for cold email.
- AuthenticationSetting up SPF, DKIM and DMARC step by step, and choosing between a quarantine and a reject policy.
- YahooThe two refusals Yahoo and AOL send most, 421 [TSS04] for complaints and 554 5.7.9 for policy, and how to clear each.
- ReputationThe usual reasons a sender reputation drops, and how to rebuild it.
Pulse · cold-email sending
Sending infrastructure that is yours alone.
Every domain gets its own MX host, IP, DKIM selector and certificate. Managed Pulse is available now, and we run it for you; the self-hosted version arrives in Q4 2026.
# on a fresh Ubuntu server
$ cd pulse && sudo ./install.sh
→ docker compose up · kumomta · stalwart · caddy
→ dashboard ready on https://pulse.yourdomain.com
$
Also from us:Beat: monitoring that tells you the fixConsulting: $65/hr, no retainer