Postmark DNS Setup Guide

Postmark DNS Setup Guide for DealEngineAI

This guide provides step-by-step instructions for configuring DNS records to optimize email deliverability with Postmark while maintaining compatibility with Office 365.

Prerequisites

  • Access to your domain's DNS management panel
  • Postmark account
  • Office 365 account (if applicable)

Step 1: Configure SPF Record

SPF records tell receiving mail servers which servers are authorized to send email from your domain.

  1. Log in to your domain registrar or DNS provider
  2. Locate the DNS management section
  3. Find existing TXT records for your domain
  4. If an SPF record exists (starts with v=spf1), you'll need to modify it
  5. If no SPF record exists, create a new TXT record

Record Details: - Type: TXT - Host/Name: @ (or leave blank, depending on your DNS provider) - Value: v=spf1 include:spf.protection.outlook.com include:spf.postmarkapp.com -all - TTL: 3600 (1 hour) or provider default

Important: Only one SPF record can exist for a domain. If you already have an SPF record, you must merge the Postmark inclusion with your existing record, not create a second one.

If You Only Use Postmark (No Office 365)

If you don't use Office 365, use this simpler SPF record:

v=spf1 include:spf.postmarkapp.com -all

Step 2: Configure DKIM Records

DKIM adds a digital signature to your emails to verify they weren't altered in transit.

  1. Log in to your Postmark account
  2. Go to Servers → Your Server → Sender Signatures
  3. Click on your domain
  4. Find the DKIM section
  5. Copy the provided DKIM record

Record Details (example - your actual values will differ): - Type: TXT - Host/Name: pm3._domainkey (use the exact subdomain Postmark provides) - Value: k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCSH5gEX... (long string provided by Postmark) - TTL: 3600 (1 hour) or provider default

Step 3: Configure DMARC Record

DMARC tells receiving servers what to do with emails that fail SPF or DKIM checks.

  1. Create a new TXT record
  2. Use the following details:

Record Details: - Type: TXT - Host/Name: _dmarc - Value: v=DMARC1; p=none; rua=mailto:dmarc@dealengineai.com - TTL: 3600 (1 hour) or provider default

Note: Replace dmarc@dealengineai.com with the email address where you want to receive reports.

Step 4: Configure Return-Path (Optional but Recommended)

Return-Path ensures bounced emails are handled properly.

  1. Create a new CNAME record
  2. Use the following details:

Record Details: - Type: CNAME - Host/Name: pm-bounces - Value: pm.mtasv.net - TTL: 3600 (1 hour) or provider default

Step 5: Verify Your Configuration

After making these changes, allow time for DNS propagation (typically 15 minutes to 24 hours).

Then verify your configuration:

# Check SPF record
nslookup -type=TXT dealengineai.com

# Check DKIM record
nslookup -type=TXT pm3._domainkey.dealengineai.com

# Check DMARC record
nslookup -type=TXT _dmarc.dealengineai.com

Or use our automated tool:

python check_dns_records.py dealengineai.com

Step 6: Set Up Inbound Email Forwarding

To process emails sent to analyze@dealengineai.com:

  1. Log in to your Postmark account
  2. Go to Servers → Your Server → Inbound

  3. Set the Inbound Webhook URL to: https://your-app-domain.com/postmark-inbound (Replace with your actual app domain)

  4. You can also run our utility to set this up: bash python setup_postmark_inbound.py

Troubleshooting

Common DNS Issues

  1. Multiple SPF Records
  2. Problem: You have more than one SPF record

  3. Solution: Combine all SPF includes into a single record

  4. Missing or Incorrect Includes

  5. Problem: SPF record doesn't include Postmark

  6. Solution: Add include:spf.postmarkapp.com to your SPF record

  7. Wrong DKIM Subdomain

  8. Problem: Using wrong subdomain for DKIM record
  9. Solution: Use exactly what Postmark provides (e.g., pm3._domainkey)

Verification

To verify your Postmark configuration is working correctly:

# Send a test email
python test_delivery.py your-email@example.com

# Check if inbound webhook is configured
python verify_postmark_inbound.py

For comprehensive email delivery troubleshooting, refer to the Email Delivery Guide.

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