Yes, there are many vendors who, provide free email address lookup service. But in free service, you can not get 100% efficiency.
You mentioned that you want to validate 10K+ email list. So, free service provider does not give facility to validate more than 100 emails for free.
They offer best features to validate email address. You can see top 10 service providers on the website homepage. There is a comparison of the top service providers, which will help you identify the service provider that best fits your requirements.As per rank, top 3 vendors are QuickEmailVerification.com, Xverify.com, Zerobounce.net.