/deliverability-checker

name: deliverability-checker
description: "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"
license: MIT
metadata:
  author: ClawFu
  version: 1.0.0
  mcp-server: "@clawfu/mcp-skills"

Email 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:dmarc@acme-corp.com

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](../dns-audit/) - Full DNS health check

Skill Metadata

• **Mode**: centaur

category: email-tools
subcategory: deliverability
dependencies: [dnspython]
difficulty: beginner
time_saved: 2+ hours/week