We are using AWS SES for sending emails. We send 10M+ emails per month using SES. For some users we received SQS bounce response status = 'undetermined', sub_status = 'undetermined'.
We mark users with bounce status 'undetermined' as hard bounce and don't send them email in future. However we found these emails are valid. Emails should be delivered successfully. We observed this for multiple emails.
Question:
1) Why 'undetermined' bounce response is received even for valid emails?
2) Should bounce response with 'undetermined' status be marked as hard bounce? Is the logic correct?
SES bounce status & sub status details are in this link: http://docs.aws.amazon.com/ses/latest/DeveloperGuide/notification-contents.html