Check their company website
Look at their LinkedIn profile
Search their name with their company domain
Use a professional email finder tool
Check public author bios or contact pages
Search press releases or conference speaker pages
Guess common email formats and verify carefully
Check WHOIS records for personal websites
Look through their social media profiles
Ask a mutual contact for an introduction
Contact them through a public form and request their email
Use email permutation tools to test likely addresses
Search old newsletters, PDFs, or documents with their contact details
Review public directories or alumni pages