the dnsconf command should also specify, in addition to SPF and DKIM, a DMARC record.
See https://dmarc.org/ for the specifications.
mail-tester recognize it and tells if it is present or not.
Here is a sample working record (which does not implement anything usefull, just saying to do nothing w.r.t DMARC):
_dmarc 10800 IN TXT "v=DMARC1; p=none"
- Target version set to 2.4
- Status changed from New to Resolved
Done in https://github.com/YunoHost/yunohost/commit/4a787da4402ceeac85ca72f7c20ed38328228f6c ;
It's just a basic and dummy DMARC support.
DMARC could be a lot more complicated (ex:
v=DMARC1; adkim=s; aspf=r; p=none; rua=mailto:firstname.lastname@example.org;), but I don't know by now what settings YunoHost might use.