Of course, even given the warmth of a photo, users should be aware that even though it us using a cryptographic hash, Gravatar may be leaking out your email address and allowing your comments to all be aggregated across the web. If you're worried about your privacy and not leaking out your personal email address, you might consider using a single-use or "throw away" email address and be aware that your data may not be completely secure in using Gravatar.

see also: https://www.wordfence.com/blog/2016/12/gravatar-advisory-protect-email-address-identity/