---
title: "Deliverability Hub: Cold Email Playbooks & Research"
description: "Operator playbooks from an agency sending a million cold emails a month, and original research measured on live sending infrastructure. Free, no signup."
url: https://warminboxes.com/deliverability-hub
breadcrumb: "Home > Deliverability Hub"
---
# Deliverability Hub

Operator playbooks from an agency sending a million cold emails a month, and original research measured on live sending infrastructure. Free, no signup.

## Deliverability playbooks

Operator strategies from an agency sending a million cold emails a month.

- [The 2026 Inboxing Playbook](https://warminboxes.com/inboxing-playbook) — A clean operator guide for building cold email infrastructure that survives longer, routes smarter, and keeps campaigns out of spam.

- [The Ultimate Liquid Syntax Guide: Hidden Ways To Personalize Cold Emails Using Your Sequencer](https://warminboxes.com/playbooks/liquid-syntax-guide) — How to make cold emails feel timely, human, and relevant at scale with Liquid syntax, smarter conditional logic, and better sending context.

- [How to Avoid the SPAM Plague in 2026: The Complete List Verification, ESP, ESG & Role Segmentation Playbook](https://warminboxes.com/playbooks/spam-plague-segmentation-playbook) — A field-tested cold email segmentation system for cleaner lists, better inbox routing, sharper persona-based copy, and higher reply rates before you ever launch.

## Deliverability studies

Original research measured on live sending infrastructure.

- [Does a SURBL listing actually hurt cold email? We tested 2,817 sending domains](https://warminboxes.com/research/surbl-blocklist-study) — A DNS sweep of every live sending domain, not a sample. 43.3% were listed. Reply rate before and after listing: 1.14% to 1.16%. Own infrastructure came back 2.3x cleaner than bought-in stock.