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
Skill Metadata
category: email-tools
subcategory: deliverability
dependencies: [dnspython]
difficulty: beginner
time_saved: 2+ hours/week
majiayu000