In plain words
Microsoft combines SPF, DKIM, DMARC and other signals into compauth=pass, fail, softpass or none, with a three-digit reason code. Reason 001 means the domain published no records, or only weak ones.
Why it matters to a firm
For a domain with no DMARC policy, or one at p=none, the verdict rests on Microsoft’s own judgement instead of a rule the firm published.
The check behind the finding
In Outlook, open the message’s headers and find Authentication-Results. Read compauth= and reason=.