Before you increase limits please look at the service quotas and best practices listed below for SES.
Hi, About the service limit, AWS would be reviewing the use-case and then allow you with what best works. And this is for the account and region. About having multiple accounts with each client, it would be great just that you need to ensure that you have the access privilege to send emails or send bulk emails.
I've also authored a blog post about SES - Amazon SES and everything to set it up which would help you understand which API suits best for your use-case.
We at AlphaResearch - Edgar Company Search send out 60,000 emails per day. You can simply ask SES to increase your sending limit. Also make sure to only send emails to users who wish to hear from you and do not spam them or your IP and domain will be banned very quickly.
I would go with option 1 which is asking AWS to increase the limit. We at Finsheet - Stock and Crypto Price for Excel and Google Sheets also ran into the limit issue initially but we reached out to AWS and was able to increase the limit to meet our needs
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