Tranport Agent: How do I know which group an email belong to?

I'm trying to write transport agent for Exchange Server 2019.

In my organization an email will belong to one or more mail groups, and I want to know which group the email belongs to in the exchange server.

I want to apply policy for a group email But I don't know How do I know which group an email belong to.

For example: test01 belong to Dev group.

How can I Know that.