I am trying to use AWS services to implement a real-time email-sending feature for one of my projects. It is like someone uses my app to schedule a reminder from my project and then the email will be sent to them nearby or at the actual time that he scheduled.
I know the AWS services such as AWS CloudWatch rules (CRONs) and DynamoDB stream (TTL based). But that is not perfect for such a feature. Can anyone please suggest a better way to implement such a feature?
Any type of guidance is acceptable.
-- Thanks in advance.
Imagine your service at huge scale. At such scale, there are likely to be multiple messages going off every minute. Therefore, you could create:

A database that stores the reminder times (this could be DynamoDB or an Amazon RDS database)
An AWS Lambda function that is configured to trigger every minute

When the Lambda function is triggered, it should check the database to retrieve all reminders that should be sent for this particular minute. It can then use Amazon Simple Email Service (SES) to send emails.
If the number of emails to be sent is really big, then rather than having the Lambda function call SES in series, it could put a message into an Amazon SQS queue for each email to be sent. The SQS queue could then trigger another Lambda function that sends the email via SES. This allows the emails to be sent in parallel.
Real time email feature using AWS services