Is it reasonable to be concerned an SES object won't be available in S3? - amazon-s3

Question

I've setup SES Rule in the following way:
Actions:
1) S3: Saves SES object to an S3 bucket
2) Lambda: Triggers my lambda function for email processing
In my testing, I've always been able to retrieve my SES object from the bucket using the messageID in the very first line of code. I'm then able to parse and read it without issue.
My question is, is it reasonable to be concerned that the SES object may not always be immediately available? I'm considering adding error handling incase the object isn't there. Basically to wait 1/2 a second and try again until the lambda times out. But I don't want to complicate the code if this is not a reasonable concern, handled by boto3, ect. Thoughts?

Answer 1

In your case, it is best to use only one S3 action configured with a notification on a SNS topic and have your Lambda subscribe to this topic.
Your Lambda will receive a SNS event containing a stringified SES event in the message:
{
"Records": [
{
"EventSource": "aws:sns",
"EventVersion": "1.0",
...
"Sns": {
"Type": "Notification",
"MessageId": "...",
"TopicArn": "...",
"Subject": "Amazon SES Email Receipt Notification",
"Message": "<STRINGIFIED SES EVENT>",
...
}
}
]
}
If you parse the Message, you will get something like this:
{
"notificationType": "Received",
"mail": {
"timestamp": "...",
"source": "...",
"messageId": "...",
"destination": [
...
],
"headersTruncated": false,
"headers": [
...
],
"commonHeaders": {
"returnPath": "...",
"from": [
"..."
],
"date": "...",
"to": [
...
],
"messageId": "...",
"subject": "..."
}
},
"receipt": {
...
"action": {
"type": "S3",
"topicArn": "...",
"bucketName": "<YOUR_BUCKET>",
"objectKey": "<YOUR_OBJECT_KEY>"
}
}
}
where you will find the exact reference to the uploaded object in your bucket (receipt.action.bucketName and receipt.action.objectKey).
With this setup, it reasonable to consider that when your Lambda is triggered the object is available.