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What is AWS?
What is Amazon SES?
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Check reputation metrics of your AWS account
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Connecting AWS account with MailBluster
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Disable open tracking for all campaigns sent from your Brand
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Resolve IP blocks that hurt email delivery and open rate

Last update: August 31, 2025

If you want to resolve IP blocks that hurt email delivery and open rate, it’s important to understand why these issues occur. Based on our work with AWS customers, seeing an IP address on a spam list is surprisingly common. There are several reasons behind this problem, and knowing them will help you fix it.

Why IP Blocks Happen

1. Shared IP Pool
By default, AWS sends emails through a shared IP pool. Other AWS users may have already used these IP addresses, and if they engaged in poor sending practices, the IP may appear on spam lists. As a result, your campaigns can suffer even though you didn’t cause the problem.

2. New IP Address
When you switch from another service to AWS, you start sending emails from a new IP. Email Service Providers (ESPs) don’t immediately trust this IP, even if your sender domain is valid. Therefore, it’s better to start with a small volume of emails and gradually increase sending. This process, known as “warming up” an IP, builds reputation and improves deliverability.

How to Resolve IP Blocks and Improve Deliverability

To resolve IP blocks that hurt email delivery and open rate, follow these actionable steps:

1. You might have an issue in SPF record, so you need to look into it.

2. Improve your email.  Too many images make your email bulky. Bulky emails are tough to deliver and impact deliverability. We have seen customers getting better output by sending simple text emails. It looks like a personal email.

3. Avoid adding any URLs other than your sending domain to your email content. For example, don’t use URL from sendgrid.com or similar.

4. Set Action URL from the Settings > Custom URL section. Add your own domain/subdomain. It will improve deliverability. It’s part of point 3.

5. Personalize your email campaign. For example, it’s better to write Hi {{first_name}}, instead of Hi Guys,. To ESPs, it means you know who you are sending emails to and each email is different.

6. Create email campaigns using drag and drop editor. It creates better HTML code that supports all types of devices and ESPs.

IP blocks can seriously harm your campaigns. However, when you understand why they happen and apply the right fixes, you can quickly improve deliverability. By focusing on authentication, personalization, and sending practices, you’ll be able to resolve IP blocks that hurt email delivery and open rate while keeping subscribers engaged. For more detailed information, you can read this blog: https://mailbluster.com/blog/the-ultimate-guide-on-how-to-prevent-your-email-newsletters-from-going-to-spam. If you can follow this correctly, it would definitely help you a lot.