How do I avoid Amazon SES email high bounce rates?

Resolution

Use a bounce and complaint monitoring system

To avoid high bounce rates, it's a best practice to implement a bounce and complaint monitoring system. You can use the following mechanisms to monitor bounce and complaint sending activity and rates.

Note: It's a best practice to use Amazon Simple Notification Service (Amazon SNS) or event publishing as your monitoring system to get the most information.

Amazon SNS

Use Amazon SNS to monitor bounces, complaints, and deliveries. You must configure Amazon SNS notifications on each identity that you want to monitor. For more information, see Amazon SNS notification examples for Amazon SES.

Event publishing

To use event publishing to monitor email sending, you must create a configuration set. Event publishing only works when you use a configuration set while you send the message. You can configure a default configuration set for each active sending identity, or specify your configuration set when you send email.

Also, set up an Amazon SNS event destination or an Amazon Data Firehose event destination. An event destination allows you to get detailed information in JSON format. See example event records for Amazon SNS and Data Firehose.

Email feedback forwarding

Email feedback forwarding monitors only bounces and complaints. Email feedback forwarding's turned on by default, but you can turn it off if you use an alternative monitoring system. The information that you receive from email feedback is limited compared to Amazon SNS notifications or event publishing.

Reputation metrics

You can use the reputation metrics dashboard in the Amazon SES console to monitor bounce and complaint rates. Use Amazon CloudWatch to create reputation monitoring alarms. It's a best practice to set up CloudWatch alarms to automatically pause email sending when the bounce or complaint rate exceeds a threshold.

Pausing allows you to investigate the cause of the increased bounce or complaint rate. It's a best practice to maintain a bounce rate that's under 5% and a complaint rate that's under 0.1%.

Identify what caused the increased bounce rate

To stop bounce rate increases, you must first identify the email addresses that caused the bounces. Use the information from the Amazon SNS notifications or Amazon SES event data to find the email addresses.

To identify what caused the increased bounce rate, review the bounceType and diagnosticCode fields in the Amazon SNS bounce notifications or event data. For information on bounce events, see Bounce types.

Don't send messages to the email addresses that increase your bounce rate

After you identify the email addresses that result in bounces, don't send messages to those email addresses so that your bounce rate doesn't continue to increase. Be sure to remove the email addresses from your email recipient lists.

Turn on the Amazon SES account-level suppression list

When the account-level suppression list is activated, Amazon SES adds the email addresses that result in a hard bounce to the suppression list. Subsequent messages to these addresses don't send, and the bounce rates decrease.

Resolve the root cause of the increased bounce rate

The following are the most common reasons for an increase or sudden spike in bounce rate:

• You send messages to an email list that contains recipients with mailboxes that aren't valid. This might happen if you use an incorrect or out-of-date list of recipients. You must remove any email addresses that aren't valid from the list before you send messages again. For more information, see Amazon SES best practices: Top 5 best practices for list management.
• Based on your reputation metrics, mailbox providers can block the IP address that you sent emails from. If there's too many subscriber complaints, then a mailbox provider might block your messages. To remove the block, follow the guidance on the mailbox provider's site.
• Mailbox providers can use a third-party blocklist to filter email. If you continue to send messages to a mailbox after your messages are blocked, then your bounce rate can increase. You can contact the mailbox provider or blocklist provider to get information on why your messages are blocked. After you're removed from a blocklist, you must address the issues and change your sending habits. Be sure to review the policies for removing Amazon SES IP addresses from blocklists.

Review the design of your sending application

After you identify the root cause of the increase in bounces, review the design of your sending application. The design can impact your bounce metrics. For example, your application sends a confirmation email to a user when they sign up, and the user enters an email address that's not valid. The confirmation email then results in a hard bounce. If there are issues on the recipient's mailbox, then you might continue to get bounces.

For more best practices and actions that you can take for successful email sending, see Building and maintaining your lists. For more information on ways to keep a low bounce rate, see What can I do to minimize bounces?

Automate how bounces process

You can also implement a solution to automate how bounces process. For examples, see Handling bounces and complaints and Maintaining a healthy email database with AWS Lambda, Amazon SNS, and Amazon DynamoDB.

Related information

Best practices for sending email using Amazon SES

What is considered a soft bounce on Amazon SES, and how can I monitor soft bounces?

Configuring notifications using the Amazon SES console

Understand email delivery issues