Validate Over 100,000 Emails

Whats the best way to validate these?

And by best I mean cheapest lol, but not too cheap to where its ass. I've tried a few free ones, but they don't get the job done. Willing to share a few list of hundreds if anyone can help me out !

Good validation services are going to be expensive. Especially for anything over 100k Not sure of any specific sellers but they shouldn't be too hard to find with google search.