Deliverability Checker Skill for Claude
Check email deliverability and DNS configuration. Use when: diagnosing email delivery issues; setting up new email domains; auditing email authentication; checking SPF/DKIM/DMARC; troubleshooting spam folder issues
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/guia-matthieu/clawfu-skills --skill deliverability-checkerWhat comes with it
12 172 bytes besides the instructionThe instruction itself
22 sections, as written by the authorEmail Deliverability Checker
> Diagnose email deliverability issues by checking SPF, DKIM, DMARC, and other DNS records - fix why your emails land in spam.
When to Use This Skill
- Delivery troubleshooting - Emails landing in spam
- New domain setup - Configure email authentication
- Migration audit - Verify email config after domain change
- Client onboarding - Check client email health
- Compliance check - Ensure proper authentication
What Claude Does vs What You Decide
| Claude Does | You Decide |
|-------------|------------|
| Structures analysis frameworks | Metric definitions |
| Identifies patterns in data | Business interpretation |
| Creates visualization templates | Dashboard design |
| Suggests optimization areas | Action priorities |
| Calculates statistical measures | Decision thresholds |
Dependencies
pip install dnspython click
Commands
Full Audit
python scripts/main.py audit example.com
python scripts/main.py audit example.com --output report.html
Check SPF
python scripts/main.py spf example.com
Check DKIM
python scripts/main.py dkim example.com --selector google
python scripts/main.py dkim example.com --selector default
Check DMARC
python scripts/main.py dmarc example.com
Check MX Records
python scripts/main.py mx example.com
Examples
Example 1: Full Email Audit
python scripts/main.py audit acme-corp.com
# Output:
# Email Deliverability Audit: acme-corp.com
# ──────────────────────────────────────────
# MX Records: ✓ Found (Google Workspace)
# SPF: ✓ Valid
# DKIM (google): ✓ Valid
# DMARC: ✗ Missing (CRITICAL)
#
# Score: 75/100
#
# Issues Found:
# 1. [CRITICAL] No DMARC record found
# Fix: Add TXT record for _dmarc.acme-corp.com
# Value: v=DMARC1; p=none; rua=mailto:[email protected]
Example 2: Diagnose SPF Issues
python scripts/main.py spf newsletter-sender.com
# Output:
# SPF Analysis: newsletter-sender.com
# ────────────────────────────────────
# Record: v=spf1 include:_spf.google.com include:sendgrid.net ~all
#
# Status: ✓ Valid
#
# Authorized Senders:
# - Google Workspace (include:_spf.google.com)
# - SendGrid (include:sendgrid.net)
#
# Policy: ~all (soft fail)
# Warning: Consider changing to -all (hard fail) for better security
Email Authentication Records
| Record | Purpose | Location |
|--------|---------|----------|
| SPF | Authorize sending servers | TXT on root domain |
| DKIM | Cryptographic signature | TXT on selector._domainkey |
| DMARC | Policy and reporting | TXT on _dmarc subdomain |
| MX | Mail delivery servers | MX on root domain |
Common SPF Includes
| Provider | SPF Include |
|----------|-------------|
| Google Workspace | include:_spf.google.com |
| Microsoft 365 | include:spf.protection.outlook.com |
| SendGrid | include:sendgrid.net |
| Mailchimp | include:servers.mcsv.net |
| Amazon SES | include:amazonses.com |
DKIM Selectors by Provider
| Provider | Common Selector |
|----------|-----------------|
| Google Workspace | google |
| Microsoft 365 | selector1, selector2 |
| SendGrid | s1, s2 |
| Mailchimp | k1 |
Deliverability Score Factors
| Factor | Weight | Impact |
|--------|--------|--------|
| Valid MX | 20% | Can't receive replies |
| Valid SPF | 25% | Server authorization |
| Valid DKIM | 25% | Message integrity |
| Valid DMARC | 30% | Policy enforcement |
Skill Boundaries
What This Skill Does Well
- Structuring data analysis
- Identifying patterns and trends
- Creating visualization frameworks
- Calculating statistical measures
What This Skill Cannot Do
- Access your actual data
- Replace statistical expertise
- Make business decisions
- Guarantee prediction accuracy
Related Skills
- dns-audit - Full DNS health check
Skill Metadata
- Mode: centaur
category: email-tools
subcategory: deliverability
dependencies: [dnspython]
difficulty: beginner
time_saved: 2+ hours/week
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How to use it
Take guia-matthieu/deliverability-checker from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.
The instructions reference pip.
Without those the skill loads but fails at the first command.