Historic complaint rate in SES Dashboard shows 0.08% (close to warning), but cloudwatch shows 0.0008% - how come?

The discrepancy between the complaint rates shown in the SES Dashboard and CloudWatch can be attributed to several factors:

1. Calculation method: The SES Dashboard likely includes all complaints received, including those from ISPs that forward complaint feedback to Amazon SES. CloudWatch metrics, on the other hand, may only reflect complaints that were directly received through SNS notifications.

2. Time frame: The SES Dashboard might be showing a longer-term historical average, while CloudWatch could be displaying a more recent, shorter time frame.

3. ISP feedback: Not all ISPs forward complaint feedback to Amazon SES. The SES Dashboard may be accounting for complaints from a broader range of sources, including estimates for ISPs that don't provide feedback.

4. Metric definitions: The SES Dashboard's complaint rate might be calculated differently from the CloudWatch metric, potentially including additional data points or using a different formula.

Given this information, it's generally advisable to trust the SES Dashboard for a more comprehensive view of your account's reputation and complaint rate. The SES Dashboard is designed to provide a holistic picture of your sending reputation, including data from various sources and calculations that may not be reflected in CloudWatch metrics alone.

If you're concerned about the higher complaint rate shown in the SES Dashboard, it's recommended to take proactive measures to reduce complaints, such as implementing a double opt-in strategy, purging lists of inactive addresses, and identifying factors that may be causing recipients to issue complaints against your emails. Additionally, you can use the new Virtual Deliverability Manager (VDM) Advisor feature in Amazon SES to receive automated recommendations and notifications when your complaint rates approach or exceed acceptable levels.
Sources
SES Complaints Rate in Reputation metrics | AWS re:Post
Amazon SES email sending complain | AWS re:Post
Reputation dashboard messages - Amazon Simple Email Service
Amazon SES now offers automated complaint rate recommendations - AWS
Amazon SES Sending review process FAQs - Amazon Simple Email Service