DMARC support with MailPoet sending service

Hello,

I’ve used your mail sending tester with the Welcome email of our newsletter (please see linked page).

It says “you don’t have a DMARC recording”.
There’s an explanation below but I don’t know if it’s something I can do on my end.

Could you tell me more about this?

(Also, a few possible improvements below?)

-0.105 FROM_EXCESS_BASE64 From: base64 encoded unnecessarily
-0.249 HEADER_FROM_DIFFERENT_DOMAINS From and EnvelopeFrom 2nd level mail domains are different
-0.01 T_KAM_HTML_FONT_INVALID Test for Invalidly Named or Formatted Colors in HTML

Thank you.

The page I need help with: [log in to see the link]