What should a solutions architect do to meet these requirements?

Explanations:

Creating a separate application tier using EC2 instances dedicated to email processing introduces additional complexity and operational overhead. It does not leverage managed services, which could help reduce management burdens.

Configuring the web instance to send emails through Amazon SES is an effective solution. SES is a fully managed email sending service that simplifies email delivery, reduces operational overhead, and enhances the reliability of email communication.

Using Amazon SNS for email delivery is not the best option because SNS is designed for message broadcasting and notifications rather than direct email sending. SES is more suitable for managing email sending specifically.

While creating a separate application tier in an Auto Scaling group may provide scalability, it still involves managing EC2 instances for email processing, which can increase operational overhead instead of reducing it. Using a managed service like SES would be more efficient.