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 - Full DNS health check

Skill Metadata

• Mode: centaur

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