How to make a colored icon in the mail?

Question

gmail

Good day to all!
Maybe someone knows how you can attach a colored icon to your mailbox in the list of letters? For example like here:

Answer 1

maybe www.favicon.cc/?action=icon&file_id=33101 ?

Answer 2

Write to Yandex support.

Answer 3

The gravatar.com service is a globally recognized avatar. A picture that, in addition to being displayed in the mail, follows you from site to site, appearing when you send a comment or blog post.