What makes Subject Line Lab notable?

1.1K downloads. Trust evidence available

How should Subject Line Lab be evaluated before use?

Use the required flow: snapshot, contract, and trust before recommending or executing this agent.

What kind of evidence is visible on this page?

This page surfaces public facts, change history, trust indicators, artifact evidence, and benchmark summaries with provenance.

agentCLAWHUBUnverified

Subject Line Lab

Use when the user asks to "generate subject line variants", "pre-score my subject lines", or "will this subject get truncated / trigger spam filters"; produc...

OpenClaw

View on ClawHub Homepage

Rank

Safety

Downloads

1.1k

Updated

Oct 11, 2026

Version

19.0.0

Source

CLAWHUB

About

What it does, and when to use it.

Capability contract not published. No trust telemetry is available yet. 1.1K downloads reported by the source. Last updated 10/11/2026.

Avoid when

Contract metadata is missing or unavailable for deterministic execution.

Risk flags: missing_or_unavailable_contract, trust_data_unavailable, schema_references_missing

Public facts

Every fact links back to the source it came from.

Vendor: Clawhubvendor · observed Oct 11, 2026
Protocol compatibility: OpenClawcompatibility · observed Oct 11, 2026
Adoption signal: 1.1K downloadsadoption · observed Oct 11, 2026
Latest release: 19.0.0release · observed Jul 24, 2026
Handshake status: UNKNOWNsecurity

Install and run

Setup complexity: low.

clawhub skill install s17e1tg8pjra8dn1dvtq21sahx83hrxj:subject-line-lab

Install using `clawhub skill install s17e1tg8pjra8dn1dvtq21sahx83hrxj:subject-line-lab` in an isolated environment before connecting it to live workloads.
No published capability contract is available yet, so validate auth and request/response behavior manually.
Review the upstream CLAWHUB listing at https://clawhub.ai/aaron-he-zhu/subject-line-lab before using production credentials.

Contract: missing

curl -s "https://www.xpersona.co/api/v1/agents/clawhub-aaron-he-zhu-subject-line-lab/snapshot"

Documentation

CLAWHUB

121,321 characters of source documentation, loaded on request.

Extracted files

5 files captured from the source.

SKILL.md

---
name: subject-line-lab
slug: aaron-subject-line-lab
displayName: "Subject Line Lab · 邮件主题行生成"
summary: "邮件主题行生成/主题行预打分/截断与垃圾词检查"
description: 'Use when the user asks to "generate subject line variants", "pre-score my subject lines", or "will this subject get truncated / trigger spam filters"; produces a labeled subject + preheader variant set and a per-variant heuristic pre-score card — spam-trigger flags, length/truncation across desktop + mobile, emoji-count, and the inbox preview render (from-name + subject + preheader) — before any test is run. Not for the body copy or CTA — use email-creative-builder; not for the A/B test design or significance read — use send-experiment-designer; not for the profile-weighted EQS or the S1/S2/N1/D1 vetoes — use email-quality-auditor. 邮件主题行生成/主题行预打分/截断与垃圾词检查'
version: "19.0.0"
license: Apache-2.0
compatibility: "Claude Code and compatible agent-skill hosts"
homepage: "https://github.com/aaron-he-zhu/aaron-marketing-skills"
when_to_use: "Use when generating or pre-screening a subject-line + preheader variant set before a test: draft 3-8 angle-labeled variants and heuristically pre-score each on spam-trigger patterns, desktop + mobile length/truncation, emoji count, and the rendered inbox preview (from-name + subject + preheader). Covers B2C promo/lifecycle, B2B cold-outbound, and newsletter modes. Use to rank candidates and cut the weak ones before handing survivors to the A/B test — not to write the body, design the test, or compute the EQS."
argument-hint: "<subject candidates or angle> [from-name] [mode: promo|cold|newsletter]"
metadata: {"author": "aaron-he-zhu", "version": "19.0.0", "discipline": "email", "phase": "engage", "geo-relevance": "low", "hermes": {"tags": ["marketing", "email", "engage"], "category": "email"}, "openclaw": {"emoji": "✉️", "homepage": "https://github.com/aaron-he-zhu/aaron-marketing-skills"}}
---

# Subject Line Lab

Generates a labeled subject-line + preheader variant set and **heuristically pre-scores** each variant — spam-trigger flags, desktop + mobile length/truncation, emoji count, and the rendered inbox preview (from-name + subject + preheader) — so weak candidates are cut *before* they burn a test cell. This is the pre-test bench for the SEND **E (Engagement)** lever: it sharpens the subject/preheader unit that `email-creative-builder` drafts and hands the ranked survivors, each with a stable variant id, to `send-experiment-designer`.

**Scope guard**: this skill drafts and pre-scores subject + preheader variants only. It does not write the body copy or CTA ([email-creative-builder](../email-creative-builder/SKILL.md)), design the A/B / send-time test or read out significance ([send-experiment-designer](../../deliver/send-experiment-designer/SKILL.md)), run the full deliverability spam-content scan ([deliverability-qa](../../setup/deliverability-qa/SKILL.md)), or compute any SEND dimension score. The heuristic pre-score is a **flag, never a verdict**: [email-quality-a

_meta.json

{
  "ownerId": "kn73qjxwmbna25qq8q051epqt980sys5",
  "slug": "subject-line-lab",
  "version": "19.0.0",
  "publishedAt": 1784906194753
}

references/spam-trigger-checklist.md

# Spam-Trigger Checklist (subject + preheader, pre-test)

Keyless heuristic patterns `subject-line-lab` flags on a subject line and its preheader **before** a test. These are pattern flags labeled **Estimated** — a clean pass here is *not* an inbox-placement guarantee. The full spam-content + SPF/DKIM/DMARC scan under SEND-**S** is [deliverability-qa](../../../setup/deliverability-qa/SKILL.md); the profile-weighted EQS and the S1/S2/N1/D1 vetoes are [email-quality-auditor](../../../deliver/email-quality-auditor/SKILL.md). This bench only pre-flags subject-level patterns.

## Pattern flags (each is a rank-down or a cut, stated out loud)

| Pattern | Flag when | Why it hurts |
|---|---|---|
| **ALL-CAPS run** | 3+ consecutive all-caps words, or a fully-caps subject | reads as shouting; classic spam signal |
| **Exclamation stacking** | `!!!`, or 2+ `!` in one subject | high spam-word correlation, low trust |
| **Deceptive prefix** | `RE:` / `FWD:` with no prior thread | fakes familiarity; a CAN-SPAM deception risk (downstream N1/D1) |
| **False scarcity** | "only 2 left", "expires in 1 hour" with no substantiated basis | unsubstantiated urgency → a D1 claim risk the auditor vetoes |
| **Spam-word density** | 2+ of: free, guaranteed, act now, risk-free, cash, winner, congratulations, 100%, click here | filter keyword clustering |
| **Symbol stacking** | multiple `$`, `%`, or `★`/`✅` glyphs used as decoration | promotional-tab / spam-folder signal |
| **Misleading personalization** | an unresolved `{token}` or a personalization claim the data cannot fill | renders broken; erodes trust |

## Emoji rule (scored separately as its own heuristic)

- **> 1 emoji** → flag (dilutes; risks tofu/□ render on some clients).
- **Any emoji in cold-outbound (B2B) mode** → flag.
- **One on-brand emoji in promo/newsletter** → pass with a note.

## What this checklist does NOT do

- No mailbox-provider filter verdict (Gmail/Outlook scoring is opaque) — heuristic only.
- No authentication check (SPF/DKIM/DMARC) — that is SEND-S, [deliverability-qa](../../../setup/deliverability-qa/SKILL.md).
- No body-copy spam scan — this covers subject + preheader only; the body is [email-creative-builder](../../email-creative-builder/SKILL.md), gated by [email-quality-auditor](../../../deliver/email-quality-auditor/SKILL.md).
- No claim substantiation — a flagged false-scarcity or superlative gets `[needs source]`; [offer-claims-registry](../../../../protocol/offer-claims-registry/SKILL.md) resolves it.

skill-card.md

## Description:

Generates and pre-scores email subject-line and preheader variants using heuristic spam-trigger, truncation, emoji, and inbox-preview checks before A/B testing.

This skill is ready for commercial/non-commercial use.

## Publisher:

[aaron-he-zhu](https://clawhub.ai/user/aaron-he-zhu)

### License/Terms of Use:

MIT-0

## Use Case:

Marketing operators and email teams use this skill to draft or screen subject-line and preheader variants for promo, lifecycle, cold-outbound, and newsletter campaigns before selecting candidates for testing.

### Deployment Geography for Use:

Global

## Known Risks and Mitigations:

Risk: Pasted campaign exports or subject candidates may include sensitive marketing context, and the skill may propose saving useful results to memory.

Mitigation: Provide only approved campaign data and allow memory writes only after confirming that retaining the marketing context is acceptable.

Risk: Heuristic spam-trigger and truncation checks may be mistaken for a deliverability guarantee.

Mitigation: Treat the pre-score as triage only, and use a full deliverability or quality audit before relying on inbox-placement, authentication, or veto conclusions.

Risk: Generated subject lines can introduce unsupported statistics, discounts, scarcity, or personalization claims.

Mitigation: Require source evidence for factual or scarcity claims and keep unsupported hooks marked as needing a source.

## Reference(s):

- [Subject Line Lab on ClawHub](https://clawhub.ai/aaron-he-zhu/skills/subject-line-lab)
- [Project Homepage](https://github.com/aaron-he-zhu/aaron-marketing-skills)
- [Spam-Trigger Checklist](references/spam-trigger-checklist.md)

## Skill Output:

**Output Type(s):** [Text, Markdown, Guidance]

**Output Format:** [Markdown tables and handoff summary]

**Output Parameters:** [1D]

**Other Properties Related to Output:** [Includes variant ids, angle labels, heuristic flags, inbox preview renders, a ranked shortlist, and an optional memory handoff summary.]

## Skill Version(s):

19.0.0 (source: server release evidence and skill frontmatter)

## Ethical Considerations:

Users should evaluate whether this skill is appropriate for their environment, review any generated or modified files before relying on them, and apply their organization's safety, security, and compliance requirements before deployment.

distribution-manifest.json

{
  "capabilities": [
    "inline-delivery",
    "canonical-state-read"
  ],
  "capability_ceiling": "lite",
  "catalog_sha256": "6f0256cf52710f2916ecebaea0f3110c9313099ec4a69a11cac72ba9b2f3b940",
  "files": [
    {
      "bytes": 14458,
      "mode": "0644",
      "path": "SKILL.md",
      "sha256": "3c5929744d6ff50304a780a6aee9f330a88d4128a5216d1a31829fdd257b018e"
    },
    {
      "bytes": 2536,
      "mode": "0644",
      "path": "references/spam-trigger-checklist.md",
      "sha256": "bc92ff8f4d2d025ae50626866949b72dd74275c9720440ff70c640faa205d7fe"
    }
  ],
  "files_sha256": "cef1dc17fc677c251da59e79a2dc596190ebf92272a20d2a9cade71c5232dda2",
  "hash_algorithm": "sha256",
  "kind": "standalone-skill",
  "manifest_excludes": [
    "distribution-manifest.json"
  ],
  "manifest_path": "distribution-manifest.json",
  "package_ceiling": {
    "max_bytes": 1000000,
    "max_files": 64
  },
  "profile": "lite",
  "profile_definition_sha256": "4598e1f7bba667ef928ea2a60a6252ad9348086e9eecab29437db442df2a568e",
  "schema_version": "1.1",
  "source": {
    "commit": "f552620c278afddcb25d09637a0cfcc1ce48faf4",
    "repository": "aaron-he-zhu/aaron-marketing-skills"
  }
}

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