Claude skill
Infrastructure Planner
How many mailboxes do I need, and what does it cost?
Turns “I want to send 10,000 a day” into a number of mailboxes, a number of domains, a monthly cost, and a date by which it is actually sending. It always runs the comparison twice, because prewarmed and fresh are not the same purchase and the cheaper per-inbox price is not always the cheaper campaign.
What it runs
- Volume to mailboxes — At a sane number of sends per mailbox per day
- Mailboxes to domains — At the ratio that keeps a single domain from carrying the whole fleet
- Platform — Google, Microsoft 365 or an isolated Azure tenant, and what each is for
- Prewarmed against fresh — Cost per email actually delivered over the window you care about, not cost per inbox
- Warmup time — The 14–21 days fresh spends not sending, which is where the real cost hides
What you get back
- Mailboxes, domains, monthly capacity and cost
- The assumptions it used, stated out loud, because those are the numbers people disagree about
- Prewarmed and fresh side by side on delivered-email cost, with the arithmetic shown
- A first-send date, which is the number fresh pricing tends to hide
Install it
One file, from GitHub. It calls the free WarmInboxes API, so there is no key and nothing to sign up for.
mkdir -p ~/.claude/skills/infrastructure-planner curl -sL https://raw.githubusercontent.com/Huz-ai-fa/warminboxes-claude-skills/main/infrastructure-planner/SKILL.md -o ~/.claude/skills/infrastructure-planner/SKILL.md
Then just ask
You do not name the skill. Its description tells Claude when it applies.
- “How many inboxes do I need to send 10,000 cold emails a day?”
- “What does cold email infrastructure cost for 5,000 sends a day?”
- “Should I buy prewarmed or fresh inboxes?”
Every answer cites the check behind it, so anything Claude tells you can be re-run by hand. A clean result is reported clean, with nothing to buy.