cold-email-inbox-warmup

cold-email-inbox-warmup is a skill for Claude Code, Codex from swan-gtm/gtm-skills. It costs 66 tokens per session (599 once invoked), scanned A, original, MIT.

A warm-up workflow for new cold-email domains and mailboxes, or inboxes recovering from spam-folder placement.

In plain words
What is it for?
Use it to plan gradual sending, check inbox placement, and decide when a domain or mailbox is ready for campaign traffic.
Why use it?
It reduces the chance that new campaign emails go to spam before the sender has built a reliable sending history.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to plan gradual sending, check inbox placement, and decide when a domain or mailbox is ready for campaign traffic.

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Install with agentmods
npx agentmods add skills/swan-gtm/gtm-skills/cold-email-inbox-warmup
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add swan-gtm/gtm-skills --skill cold-email-inbox-warmup
Clone the repo
git clone --depth 1 https://github.com/swan-gtm/gtm-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cold-email-inbox-warmup

README.md
[![agentmods](https://agentmods.dev/badge/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup/github.svg)](https://agentmods.dev/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup)
Your own site
<a href="https://agentmods.dev/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup"><img src="https://agentmods.dev/badge/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cold-email-inbox-warmup

Your own site · 80×15
<a href="https://agentmods.dev/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup"><img src="https://agentmods.dev/badge/skills/swan-gtm/gtm-skills/cold-email-inbox-warmup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 599 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00066 $0.00599
Opus 5 $0.00033 $0.00300
Sonnet 5 $0.00013 $0.00120
Haiku 4.5 $0.00007 $0.00060

Measured 9d ago against content hash 75aae35bc7e4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

cold-email-inbox-warmup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/imad-badreddine/cold-email-inbox-warmup/SKILL.md · 38 lines

How it starts

The opening of the file, as written. The whole thing — 38 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Run this before any new domain or mailbox sends cold email. It produces a ramp schedule and a clear go/no-go decision for opening campaign volume.

The play

  1. Separate the asset from the brand: cold email runs on secondary domains, never the company's primary domain. The primary's reputation is not a chip to gamble.
  2. Give a fresh domain two weeks of silence after setup: authentication configured, mailboxes created, signatures and profile pictures in place, zero cold sends. Age is part of reputation.
  3. Warm for at least three weeks before campaign volume: start at a handful of sends per day per mailbox, grow the daily count a little every few days, and keep replies flowing; a mailbox that only sends and never receives looks like a cannon, not a person.
  4. Cap real campaign volume per mailbox at 20-30 cold sends per day, and keep warm-up activity running in the background even after campaigns start. Scale by adding mailboxes and domains, not by pushing one inbox harder.
  5. Go/no-go before launch: spot-check where warm-up messages land. Anything worse than consistent inbox placement means the ramp continues; launching into the spam folder burns the list and the domain together.
  6. On a placement drop or a bounce spike mid-campaign: cut volume in half, hold for several days, and only ramp back one step at a time: the same discipline as the initial warm-up, at smaller scale.

What good looks like

  • Good operators treat sending volume as something a mailbox earns, week by week; the mediocre version buys a domain on Monday and blasts 200 sends on Friday, then wonders why replies stopped.
  • The tell that separates experts: they watch placement and bounce rate per mailbox, not per campaign, and they act on the first bad signal instead of the fifth.
  • Consistency beats speed here exactly as on social channels: identical, boring, daily behavior is what reputation systems reward.
  • Done well, every mailbox reaches campaign volume with steady inbox placement, bounce rates stay low, and a placement incident costs days, not domains.

Read the full file on GitHub · 38 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 38 lines · 66 tokens per session scan A 75aae35bc7e4

Subscribe to this mod's changes

cold-email-inbox-warmup is a skill published in the GitHub repository swan-gtm/gtm-skills (153 stars, last pushed 2d ago), licensed MIT. It adds 66 tokens to every session and 599 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.