Low delivery rate (1.46%) to email list on AWS SES; why only 39 of 2669 emails delivered?

The low delivery rate you're experiencing is concerning and could be due to several factors. Here are some potential reasons and steps to investigate:

1. Spam filtering: Your emails may be getting caught in recipients' spam filters. This can happen even if your account is marked as "Healthy" by AWS SES.

2. Email list quality: Your email list may contain outdated or incorrect email addresses. Although you didn't see any bounces, some ISPs might silently discard emails to invalid addresses without sending a bounce notification.

3. Greylisting: Some ISPs use a technique called greylisting, where they temporarily reject emails from unknown senders. SES will retry these messages, but it can cause delays in delivery.

4. Reputation issues: If your sending IP or domain has a poor reputation with recipient ISPs, it could lead to low delivery rates.

5. Content issues: The content of your emails might be triggering spam filters.

To address this issue:

1. Verify the quality of your email list. Ensure all addresses are valid and obtained through proper opt-in processes.

2. Check your sender reputation. Use tools provided by AWS SES to monitor your bounce and complaint rates.

3. Review your email content to ensure it doesn't contain spam-like elements.

4. Consider implementing authentication methods like SPF and DKIM if you haven't already.

5. Monitor your delivery rates over time. Sometimes, delivery issues can be temporary due to greylisting or other temporary blocks.

6. If the problem persists, and you have a paid AWS Support plan, consider opening a support case with AWS for more detailed investigation.

Remember, even if you're within your sending limits, the quality of your emails and your sender reputation are crucial for successful delivery. It's important to reassess your email-sending strategy if you're experiencing consistently low delivery rates.

Sources
Amazon SES Delivery problems - Amazon Simple Email Service
Amazon SES and deliverability - Amazon Simple Email Service
Amazon SES Delivery problems - Amazon Simple Email Service
Understanding email deliverability in Amazon SES - Amazon Simple Email Service