We have configured email process in our cloud instance and reading email propert

If you configure email message properties for importance flag and don't send an email with importance flag, system does not trigger any process for that email. I don't why this happens but what you can do with your use case is that put importance flag in either subject or body of email, and parse it. For instance, you may try to send an email with subject as "Test email subject [High]" or "Test email subject [Low]", you can parse this importance flag value using extract function as extract(pv!subject_txt,"[","]") and determine whether email was of High / Low importance. You don't have to configure importance flag on data mapping with this approach any more.

If you configure email message properties for importance flag and don't send an email with importance flag, system does not trigger any process for that email. I don't why this happens but what you can do with your use case is that put importance flag in either subject or body of email, and parse it. For instance, you may try to send an email with subject as "Test email subject [High]" or "Test email subject [Low]", you can parse this importance flag value using extract function as extract(pv!subject_txt,"[","]") and determine whether email was of High / Low importance. You don't have to configure importance flag on data mapping with this approach any more.