Received emails do not have unsubscribe link in the header

Hello,
Emails received from my Mautic system are not recognized as newsletters and do not have an option in email programs to unsubscribe in the header (or at the top of the email). “list-unsubscribe” is in the header but it isn’t available as a link like it normally would be in a newsletter email (like in this picture).
2021-04-09 15_56_45-Window

The unsubscribe link in the email itself works just fine but like I said there isn’t an option in the header and it means that a lot of our emails are landing in spam. I can’t find an option anywhere where it’s disabled and have tried adding a custom header with “list-unsubscribe” but that didn’t work either.

Thanks for any help!