This article explains how to find email addresses using Google. There are also email search sites and directories to help you find the information you need.
How to Find Someone's Email Address (in Seconds)
Finding someone’s email address can be tricky. Without an email domain name to point to or an organization to classify them into (like @gmail.com or @company.com), your search immediately becomes extremely broad. However, if you know their name, you can search the internet for information about the person, which can help you determine their email address.
The easiest way to start an internet search to find someone's email address is to type in not just their name, but any information about them. The goal is to find a source that groups their identifying information with their email address.
This is the best way to find an email address: hope they have it publicly listed on their social media profile (if they have one). Use Google to search for what you know within a website you suspect they use.