Key metrics to monitor for dovecot at CloudWatch

Hello Team,

Configured dovecot mail server and SES will receive and forward to SNS topic. Lambda subscribed to the topic and it will receive the mail and write to the EFS volume. EFS volume mounted on both dovecot and lambda. Also enabled AWS Cloudwatch to monitor overall infra.

I'm going to enable anomaly detection at Cloudwatch and I want to know the list of key metrics to monitor.

I'm thinking of the following metrics.

1. No of bounce
2. PublishFailed & Success
3. EFS disk storage

Please suggest the other key metrics, so that I can enable anomaly detection to understand and create the cloudwatch alarm.