Deliverability Checker

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:[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