Due to AWS deprecating Signature Version 3 in Oct 2020 for SES, I want to handle this issue with AWS boto (Python). But I didn't see any doc related to boto supporting signature version 4 for SES. Is anyone having similar issue and have solutions?
Promoting j0nam1el's comment to an answer, as it directly answers the question:
I found where SignatureV4 support was added to boto (in 2012). However, cross-referencing this and this, it appears that the boto.ses code still uses HmacAuthV3Handler. From this, I conclude that users of the older 'boto.ses' library will not be able to continue utilizing AWS SES past 2020-10-01.
As noted in this github issue, the deadline has been extended:
We are extending support for Signature Version 3 until February 28, 2021 (the previously announced deprecation date was October 1, 2020). Beginning March 1 2021, support for Signature Version 3 will be turned off in Amazon SES, and only Signature Version 4 will be supported going forward. Amazon SES customers who are currently using Signature Version 3 must migrate to Signature Version 4 by February 28, 2021. After that, requests using Signature Version 3 will be progressively throttled in Amazon SES.
I'm not sure exactly what "progressively throttled" means - would old-style requests fail randomly, or just take longer? Please edit this answer if you know.
My recommendation is that you migrate from boto, which is essentially deprecated, to boto3 because boto3 supports signature v4 by default (with the exception of S3 pre-signed URLs which has to be explicitly configured).