Why did I get an email from AWS that states that my Amazon SNS subscriptions manually deactivated?

Short description

If messages are published to an SNS topic at a rate that exceeds the email delivery quota, then Amazon SNS deactivates the affected subscriptions. The quota is a per-subscription limit and takes effect only after Amazon SNS has evaluated any subscriptions 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. This 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 the subscriptions with more than 10 attempted email deliveries per second are deactivated. Other subscriptions with fewer than 10 emails stay active. If a subscription is 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.

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.

Related information

Common Amazon SNS scenarios

Creating a subscription to an Amazon SNS topic

Amazon SNS now supports faster automatic deletion of unconfirmed subscriptions