Use Typeform or Google Forms with email validation turned on. Ask users: "Do you prefer Hotmail?" and segment them automatically.
This example is highly simplified and assumes you're working within an ethical and legal framework. For instance, in Python, you could create a simple text file with email addresses: Hotmail Valid.txt
import re
Free verification files are typically several months old. Hotmail accounts get deleted, disabled, or abandoned. Using such a list will increase your bounce rate, harming your email sender score. Use Typeform or Google Forms with email validation turned on
If you suspect you are a victim: