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

Short description

When messages are published to an SNS topic at a higher rate than the Delivery rate for email messages quota, Amazon SNS deactivates the subscription. When deactivated, the subscription is in a "PendingConfirmation" state.

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

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

Note: Amazon SNS supports an email message delivery rate of 10 TPS to SNS topics for each AWS account. For more information, see Amazon SNS endpoints and quotas.

Resolution

It's a best practice to avoid subscribing email addresses to high-volume SNS topics. Common use cases for SNS topic email subscriptions include monitoring Amazon CloudWatch alarms and sending usage reports to multiple email addresses.

For high-volume SNS topics, it's a best practice to subscribe only high-throughput, system-to-system endpoints instead. 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