$ man inbox-kit

Inbox Kit

A service that handles secondary domain registration, inbox provider setup, DNS configuration, and mailbox provisioning in one workflow. Instead of manually buying domains, configuring Google Workspace, setting up SPF/DKIM/DMARC, and creating mailboxes one by one — Inbox Kit does it all.

Setting up 18-36 sending mailboxes across 18-36 domains manually is brutal. Each domain needs DNS records. Each mailbox needs an inbox provider account. Each account needs configuration. If you're doing it yourself, that's hours of repetitive work per campaign launch. Inbox Kit collapses that into a single workflow. Time saved compounds — especially when you're managing infrastructure for multiple partners.

I use Inbox Kit to spin up sending infrastructure for every partner campaign. I specify the number of domains and mailboxes I need, the naming conventions, and the inbox provider split (Google Workspace + Microsoft 365). Inbox Kit provisions everything — domains, DNS, mailboxes — and I connect them to Instantly for warmup. It's the fastest path from "we need email infrastructure" to "we're warming inboxes."