How can I handle a high bounce rate with emails that I send using Amazon SES?

Last updated: 2020-04-30

The bounce rate of my Amazon Simple Email Service (Amazon SES) account is higher than normal. Or, my bounce rate spiked or increased suddenly. It's putting my account at risk for an account review or a sending pause. How can I identify what's causing the increase in bounce rate? What can I do to prevent a high bounce rate?

Resolution

Identify the cause of the increase in bounce rate

To stop the bounce rate from increasing, you must identify the email addresses that are causing the bounces. To do this, you can configure bounce notifications using an Amazon Simple Notification Service (Amazon SNS) topic. From the SNS notifications, find the email addresses that are resulting in bounces. You must stop sending messages to those addresses to prevent your bounce rate from increasing further.

To identify what's causing the increase or spike in bounce rate, review the following fields in the message body of the Amazon SNS bounce notifications:

  • bounceType: A Transient bounce type is a soft bounce, which is a temporary failure or rejection that can generally be retried. A Permanent bounce type is a hard bounce, which is a persistent delivery failure or rejection from the receiving mail server. Hard bounces aren't retried, so your recipient doesn't receive the email message.
  • diagnosticCode: The code in this field provides more information on what's causing the bounces.

Some of the most common reasons for an increase or sudden spike in bounce rate include:

  • Email lists: You can get a spike in bounces if you send messages to an email list that contains recipients with invalid mailboxes. This can happen if you use an incorrect or out-of-date list of recipients. If you suspect that an incorrect email list is causing the spike in bounces, then you must stop sending messages immediately and review the email list. You must remove any invalid email addresses from the list before sending messages again. For more information on managing email lists, see Amazon SES Best Practices: Top 5 Best Practices for List Management.
  • Complaints: Based on your reputation metrics, mailbox providers can block the IP address that you're sending email from. If there's a large number of subscriber complaints, then a mailbox provider might block your messages. Follow the guidance that you find on the mailbox provider's postmaster site to remove the block. However, if you don't follow the guidance, then you risk continuing blocks.
  • Blacklisted: Mailbox providers can use a third-party blacklist to filter email. If you continue to send messages to a mailbox after your messages are blacklisted, then your bounce rate can increase. You can contact the mailbox provider or blacklist provider to get information on why your messages are blacklisted. After you're removed from a blacklist, you must address the issues and change your sending habits accordingly. Otherwise, you risk getting blacklisted again and getting more bounces. For more information, see Amazon SES IP Blacklist FAQs.

Prevent a high bounce rate

Consider the following ways to manage your bounce rates:

  • Review the design of your sending application because it can have an impact on your bounce metrics. For example, if your application sends a confirmation email to the user when they sign up and the user enters an invalid email address, then the confirmation email results in a hard bounce. Additionally, if there are issues and you set up your application to retry sending emails whenever there's a failure, then you continue to get bounces. For more recommendations on mechanisms that you can implement in your application for successful sending metrics, see Building and Maintaining Your Lists.
  • Set up a bounce and complaint monitoring system. You can use the Amazon SES reputation dashboard to check your account's bounce and complaint rates. It's a best practice to also set up Amazon CloudWatch alarms for your bounce and complaint rates, so that you're notified when these rates reach a certain threshold. With a monitoring system and notifications, you can also implement a solution to automate how bounces are processed, such as in the following examples:
    Handling Bounces and Complaints
    Maintaining a Healthy Email Database with AWS Lambda, Amazon SNS, and Amazon DynamoDB