Can a thief know my Apple ID without my PIN code? I got my iPhone stolen recently with Activation Lock on. It's been off since it has been stolen according to iCloud.

I received a phishing email attempting to get my iCloud password and I was wondering, so they have my Apple ID email address. Does that mean that they have access to my phone's data?

Would it be possible for them to know my Apple ID even if the phone was locked and they didn't know the PIN?

Thanks.
Without your PIN, the thief should not be able to get any data from the phone. The ID in the phishing mail probably is just a wild guess, I got a few of those as well over the years.