Claude skill
Cold Email Copy
Is this email going to land in spam?
The quickest way we see a domain burn is recipients marking mail as spam, and warmup, DNS and rotation do not outrun it. So copy gets checked before infrastructure, and a domain that passes every check with a campaign in spam is usually a copy or list problem. Paste the email or the sequence and this says which lines to change, most costly first.
What it runs
- Spam triggers and structure — Words, tone and layout that filters and readers both react to
- Links, images and tracking — What a link or pixel costs, and whether the tracking domain is set up right
- Gmail clipping — HTML size, so the end of the email and the opt-out are not cut off
- Spintax and merge tags — Every variant rendered, so no one receives a blank first name
- Inbox preview — How the subject and opener actually show before the email is opened
- Opt-out — A reply-based line or one-click unsubscribe, depending on who you send to
What you get back
- What each check found, with a link to re-run it
- The two or three edits that matter most, line by line, without rewriting the email unasked
- Whether it is ready to test at 5 a day per inbox, the pace any new copy starts at
- No placement promise: receivers decide, and no check can guarantee the inbox
Install it
Best installed with the plugin, which also connects WarmInboxes Free MCP, the tools this skill runs. On its own it is one file that falls back to the free WarmInboxes API, so there is no key and nothing to sign up for.
/plugin marketplace add Huz-ai-fa/warminboxes-claude-skills /plugin install warminboxes@warminboxes
Or this one skill on its own:
mkdir -p ~/.claude/skills/cold-email-copy curl -sL https://raw.githubusercontent.com/Huz-ai-fa/warminboxes-claude-skills/main/cold-email-copy/SKILL.md -o ~/.claude/skills/cold-email-copy/SKILL.md
Then just ask
You do not name the skill. Its description tells Claude when it applies.
- “Is this cold email spammy?”
- “Check my sequence before I launch it tomorrow”
- “My domain checks pass but the new campaign is landing in spam, why?”
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.