Does the protector support DKIM?

Microsoft blocks mail when the DKIM record is not ok

I can not find any thing about DKIM in the protector?

Yes, the Protector fully supports DKIM pass-through, but it does not generate or sign DKIM itself.
DKIM must be configured on your mail server (Microsoft 365, Exchange, Postfix, Sendmail, etc.).

The Protector will not modify or break DKIM-signed messages, so if DKIM is correctly enabled on your mail server, Microsoft will accept the mail without issues.

If Microsoft is blocking mail due to DKIM, it means the DKIM configuration on the mail server or DNS needs to be corrected. The Protector does not interfere with DKIM.