Some people on linkedin put their email address in their profile which makes it publicly available, especially a lot of recruiters. Click the link below to view an example;
Do your own search by changing the text after ‘keywords title’…for example, replace ‘new york city area’ with ‘sales’
site:linkedin.com (intitle:com OR gmail.com OR yahoo.com) keywords title “sales” -inurl:dir
You get over 19,000 results. If i had a sales job board, those leads would be highly useful.
Change the keyword to recruiter and I see over 6,700 results;
site:linkedin.com (intitle:com OR gmail.com OR yahoo.com) keywords title “recruiter” -inurl:dir