How to find out which sender address I am using in each individual iMessage conversation?

On my iPhone running iOS 18, in iMessage, I have multiple sender addresses including 3 phone numbers and 3 email addresses. Different from https://apple.stackexchange.com/questions/468103/how-to-use-different-sender-address-in-imessage-when-messaging-different-contact , where the OP wanted to use different sender addresses intentionally, I only want to know which address I am actually using in each existing conversation. Contacts are not all using the same default address to contact me, because I notice that iMessage will use the address that I received the message from to send responses. This starts to become an issue as I plan to remove one of these email addresses that I no longer want to use. I would like to know which contacts I need to send this update. Likely there are not many such contacts, so I don't want to send the update to everyone. Also, if I just remove it blindly and start to send messages using my new default address, then some contacts could spam my messages automatically because they don't have my new address in their Contacts.