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: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