Why did AWS send me an email stating that it manually deactivated my Amazon SNS subscriptions?

2 minute read

I want to know why I received an email stating that AWS manually deactivated my Amazon Simple Notification Service (Amazon SNS) email subscriptions.

Short description

If you publish messages to an Amazon SNS topic at a rate that exceeds the email message delivery quota, then SNS deactivates the affected subscriptions. The quota is a per-subscription limit and takes effect only after Amazon SNS has evaluated any subscription filters.

Amazon SNS deactivates subscriptions for the following reasons:

To prevent spam in the destination inboxes.
To protect the recipient email servers from message overload.
To make sure that the Internet Service Providers (ISPs) don't identify the high traffic volume as spam and block messages.

Amazon SNS supports an email message delivery rate of 10 messages per email or email-json subscription for each AWS account. The email message delivery rate is a hard limit, and you can't increase it. For more information, see Service quotas.

If you have multiple subscriptions with filter policies, then Amazon SNS deactivates the subscriptions with more than 10 attempted email deliveries per second. Other subscriptions with fewer than 10 emails stay active. If a subscription's deactivated, then it's placed in the Pending Confirmation state. Amazon SNS automatically deletes unconfirmed subscriptions after 48 hours unless you run the ConfirmSubscription API action to confirm the subscription. Amazon SNS keeps suspended subscriptions for 30 days and then automatically deletes the subscription. To confirm the subscription, run the ConfirmSubscription API action.

Resolution

For high-volume SNS topics, it's a best practice to subscribe to high-throughput, system-to-system endpoints. For example, Amazon Simple Queue Service (Amazon SQS) queues, AWS Lambda functions, or HTTP endpoints. These types of subscription endpoints support a higher transaction per second (TPS) quota.