what is the best method to send email from multiple aws services and ec2 instances?

here are three methods for sending emails from AWS services and EC2 instances

1. Amazon SES (Simple Email Service): SES is a scalable email service that allows you to send transactional and marketing emails. It integrates with other AWS services, including EC2 instances, and provides features such as email tracking, bounce handling, and feedback loops. One advantage of SES is its low cost, which is based on the number of emails sent. Additionally, SES has a high deliverability rate and is known for its reliability.

2. SMTP Relay: SMTP (Simple Mail Transfer Protocol) Relay is a method of sending email through a third-party provider, such as SendGrid or Mailgun, using the SMTP protocol. This method involves configuring an SMTP server on an EC2 instance or other server, and routing email through the third-party provider. SMTP Relay allows you to take advantage of the features provided by the third-party provider, such as email templates and email tracking, while still using your own domain name. An advantage of SMTP Relay is that it can be used with any email client or application that supports SMTP.

3. AWS Lambda + Amazon SES: Another option for sending emails is to use AWS Lambda with Amazon SES. This involves creating a Lambda function that sends emails using SES and then triggering the function from another AWS service or EC2 instance. One advantage of this approach is its scalability, as Lambda can handle large volumes of emails without the need for dedicated infrastructure. Additionally, Lambda provides an easy way to integrate with other AWS services, and SES provides the same features as described above.