I’m currently testing a high throughput email sending application and leveraging AWS SES Email Receiving to verify successful delivery of sent emails. (Since the goal is to test sending of thousands of emails, thought that SES should handle such throughputs much better than regular email servers). Here’s what I have done so far:

1. Setup:

   • Configured an SES rule set to receive anything sent to one of our subdomains.
   • Set the rule set action to store received emails in an S3 bucket.

2. Observation:

   • The setup works as expected for lower email volumes.
   • However, when sending a large volume of emails (~20 per second), only a fraction of them are being stored in the S3 bucket.

Specifics:

• Sending around “50” emails results in only “20-30” emails getting delivered to S3.

Question:
What could be causing this discrepancy, and what steps can I take to troubleshoot or resolve this issue?

Additional Context:

1. SES Dashboard shows 0 bounces or complains for the sent emails. (We also use SES to send emails, and the sending metrics of the high throughput App report no Bounces or Complains)
2. Tried checking CloudWatch “SES->Receipt Rule Set Metrics”, it shows 0 PublishFailures, however “Received” metric is way lower than even the actual number of published emails, so those Metrics seem to be useless…
3. The S3 bucket permissions are correctly configured to allow SES to write to it.
4. Are there any SES limitations or throttling policies that might affect high-volume email receiving and storage in S3?

Looking for insights or similar experiences from the community. Any guidance on troubleshooting steps or configuration checks would be highly appreciated.

Thank you!