Mail tester swears at base64 encoded email part uses line length greater than 79 characters?

Question

gmail

Mail tester says base64 encoded email part uses line length greater than 79 characters.

I don't know how to solve this problem. Someone can help?

Answer 1

It was necessary to add the service header Content-Transfer-Encoding: base64

Answer 2

base64 strings in your emails must not exceed 79 characters.