What is the safest email provider that is free?

I understand the importance of choosing a secure email provider, especially when dealing with sensitive information like cryptocurrency transactions. So, my question is, what is the safest email provider available for free that can offer robust security features to protect my data from unauthorized access? Is there a particular provider that stands out in terms of encryption, spam filtering, and privacy policies? I'm looking for a reliable and trusted option that doesn't compromise on security just because it's free.