Amazon Simple Email Service is ending support for Signature Version 3 effective September 30, 2020

Like most of AWS Simple Email Service clients, we have been notified that Amazon Simple Email Service is ending support for Signature Version 3 effective September 30, 2020.

https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html

The above link and this one (https://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html) seem to suggest that if we use AWS SDK, the signing process is handled automatically.

This leads me to believe that we just need to ensure we are using the latest versions of AWS SDK? Is this correct?

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Also, one test to see which version is used for signing seems to be inspecting the HTTP API request for:

GET https://iam.amazonaws.com/?Action=ListUsers&Version=2010-05-08 HTTP/1.1
Authorization: AWS4-HMAC-SHA256 Credential=AKIDEXAMPLE/20150830/us-east-1/iam/aws4_request, SignedHeaders=content-type;host;x-amz-date, Signature=5d672d79c15b13162d9279b0855cfba6789a8edb4c82c400e06b5924a6f2b5d7
content-type: application/x-www-form-urlencoded; charset=utf-8
host: iam.amazonaws.com
x-amz-date: 20150830T123600Z

In other words, if version 4, "Authorization: AWS4-HMAC-SHA256" will be seen. I am not sure when this HTTP API Request is sent.

Is this when we use AWS SDK to create the AmazonSimpleEmailServiceClient ?

 Dim client As New Amazon.SimpleEmail.AmazonSimpleEmailServiceClient("<Access-key-id>", "<Secret-access-key-id>", Amazon.RegionEndPoint.<EndPoint>)

Or when we send the email request?

Dim mailObj As New SendEmailRequest
...
Dim response = client.SendEmail(mailObj)

Thanks Thomas, if your comment was an answer I would have accepted it :-)

I inspected the HTTP request header using fiddler as it sends the email.

And can confirm that it was using Signature version 3.

Then I moved to AWS SDK 3.3, and inspected the HTTP header and found out that the Signature is version 4.

So it does appear that all we need to do is upgrade our AWS SDK. Thanks.

Hope this helps someone else.