Amazon SES messages to SNS and SQS optimization

Question

I am using Amazon SES for a project and have set up a Receipt rule to send messages from SES to SNS. The SNS has my API end point as a subscriber but to ensure that I do not miss any message I have also set up an SQS Queue and have subscribed the queue to SNS topic.

With this set up I receive each SES email twice. (One from SNS and one with a poll in SQS). Is there a way to send only the failed SNS messages to SQS queue so that I don't have to check for duplicates always ?

Rule which sends SES messages to SNS:

SQS queue subscribed to SNS topic:

Answer 1

Short answer, no.

If you've subscribed an SQS queue to an SNS topic, it'll receive all messages published to the latter. SNS doesn't know which messages were successfully processed by your API, so can't selectively send to SQS.

Answer 2

With your setup, it's not possible to do so. But there are other approaches that you can try out. It might introduce complexity into your application, but it's worth trying. Some of the approaches are given below.

1. SES to SNS and send all messages from SNS to SQS, and poll SQS for the messages. If some fail, put them to a Deadletterqueue (similar to SQS), and poll that queue separately from time to time, to look for failed messages. This makes the messages more persistent, but slightly inefficient due to polling.

2. SES to SNS and let SNS use it's delivery policy as needed. You can avoid an SQS, and ask SNS to look for the delivery status, and retry if it is a failure. You can define the retry policy as needed and it's given in this link. After a lot of trying, the message can be discarded as a total failure. You can also write to AWS CloudWatch Logs on the status of the retries.