Problem Summary
If you’re comparing SendGrid and Postmark delivery rates and seeing significant differences, you’re likely experiencing email deliverability issues that could be costing you customers and revenue. Both platforms are solid choices in 2025, but understanding why one might be performing better than the other for your specific use case is crucial for your business communication strategy.
Step-by-Step Fixes
Step 1: Check Your Authentication Records
Start by verifying your domain authentication settings for both services. Log into your SendGrid dashboard and navigate to Settings > Sender Authentication. For Postmark, go to your Server settings and click on DNS Records. Make sure all SPF, DKIM, and DMARC records are properly configured and showing green checkmarks.
If any records show errors, copy the provided DNS values and update them in your domain registrar’s DNS settings. This usually takes 24-48 hours to fully propagate, but you might see improvements within a few hours.
Step 2: Analyze Your Sending Reputation
SendGrid provides a reputation score in your dashboard under Analytics > Reputation. Look for any sudden drops or consistently low scores. Postmark shows this information in the Activity tab with their bounce and spam complaint rates.
If your reputation is below 80% on SendGrid or you’re seeing bounce rates above 5% on Postmark, you need to clean your email list immediately. Both services offer built-in suppression lists that automatically remove bad addresses.
Step 3: Review Your Email Content
Open your recent email campaigns in both platforms. SendGrid’s Email Testing tool and Postmark’s SpamAssassin integration can help identify content issues. Look for spam trigger words, excessive use of capital letters, or too many links.
Try sending a simple text-based test email through both platforms to the same recipient list. If delivery rates improve dramatically, your HTML templates or content might be the culprit.
Step 4: Compare API Implementation
Check your code implementation for both services. Here’s a basic comparison structure you should verify:
“`javascript
// SendGrid Implementation
const sgMail = require(‘@sendgrid/mail’);
sgMail.setApiKey(process.env.SENDGRID_API_KEY);
const msg = {
to: ‘[email protected]’,
from: ‘[email protected]’,
subject: ‘Test Email’,
text: ‘Testing delivery rates’,
html: ‘
Testing delivery rates
‘
};
// Postmark Implementation
const postmark = require(‘postmark’);
const client = new postmark.ServerClient(process.env.POSTMARK_API_KEY);
client.sendEmail({
From: ‘[email protected]’,
To: ‘[email protected]’,
Subject: ‘Test Email’,
TextBody: ‘Testing delivery rates’,
HtmlBody: ‘
Testing delivery rates
‘
});
“`
Make sure you’re using verified sender addresses and that your API keys have the correct permissions.
Step 5: Test with Different Email Providers
Create test accounts on Gmail, Outlook, Yahoo, and Apple Mail. Send identical emails through both SendGrid and Postmark to these addresses. Check not just the inbox, but also spam folders and the Promotions tab in Gmail.
Document which service delivers to which provider more reliably. You might find that SendGrid works better for B2B domains while Postmark excels with consumer email providers, or vice versa.
Step 6: Enable Detailed Tracking
Turn on open tracking and click tracking in both platforms. SendGrid calls this “Tracking Settings” while Postmark lists it under “Message Streams.” This data will help you understand not just delivery, but actual engagement rates.
Likely Causes
Cause #1: Different IP Pool Quality
SendGrid uses shared IP pools by default unless you’re on their Pro plan, while Postmark maintains highly curated shared IPs with strict approval processes. This means your SendGrid emails might be sharing reputation with other senders who aren’t following best practices.
To check this, look at your SendGrid IP reputation under Settings > IP Addresses. If you see fluctuating scores, consider upgrading to a dedicated IP. For Postmark, their shared IPs are generally reliable, but you can request IP information from their support team.
Cause #2: Message Stream Configuration
Postmark separates transactional and broadcast emails into different message streams, each with its own reputation. SendGrid combines everything unless you specifically configure subusers or separate API keys.
Review your Postmark Message Streams settings and ensure you’re not mixing marketing emails with transactional ones. For SendGrid, create separate API keys for different email types and monitor their performance independently.
Cause #3: Bounce Handling Differences
SendGrid and Postmark handle bounces differently. SendGrid might retry soft bounces more aggressively, while Postmark tends to be more conservative. This can make SendGrid’s delivery rates look higher initially, but could hurt long-term reputation.
Check your bounce logs in both platforms. SendGrid shows this under Activity > Bounces, while Postmark displays it in the Activity feed with detailed bounce reasons.
When to Call a Technician
If you’ve tried all these steps and still see delivery rate discrepancies over 20% between platforms, it’s time to bring in an email deliverability specialist. This is especially true if you’re sending more than 100,000 emails per month or if email is critical to your business revenue.
Look for consultants who are certified by both SendGrid and Postmark. They can perform deeper diagnostics, including IP warming strategies, custom authentication setups, and advanced reputation management that goes beyond basic troubleshooting.
Don’t wait if you’re seeing sudden drops in delivery rates across both platforms – this could indicate your domain has been blacklisted, which requires immediate professional intervention.
Copy-Paste Prompt for AI Help
Here’s a prompt you can use with ChatGPT or Perplexity to get more specific help:
“I’m comparing email delivery rates between SendGrid and Postmark. SendGrid shows [X]% delivery rate while Postmark shows [Y]% for the same email list. My domain is authenticated on both platforms. I’m sending [type of emails] to approximately [number] recipients [frequency]. The main recipient domains are [list top 3 domains]. Can you help me diagnose why there’s a difference and suggest specific settings I should check on each platform? I’m using [programming language/framework] for integration.”
Remember to replace the bracketed placeholders with your actual data for the most helpful response.