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

Short description

If messages are published to an SNS topic at a higher delivery rate for email messages quota, then Amazon SNS deactivates those subscriptions. The limit is a per-subscription limit, and is applied only after Amazon SNS has identified any filters that were set up on the subscriptions.

Amazon SNS automatically deactivates subscriptions when transaction per second (TPS) quotas are breached for the following reasons:

• To prevent spamming the destination inbox with events.
• To protect the recipient mail server from being flooded with messages.
• To avoid Internet Service Providers (ISPs) identifying elevated traffic as spam and blocking messages from delivery.

Amazon SNS supports an email message delivery rate of 10 TPS to SNS topics for each AWS account. 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 the subscription is in the PendingConfirmation state.

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 TPS quota.

Related information

Common Amazon SNS scenarios

Sending email in Amazon Pinpoint

Subscribing to an Amazon SNS topic

Publishing to a topic