DMARC requires usage of DKIM and SPF (which is mandatory for promio.connect domains). Basics can be found here: https://en.wikipedia.org/wiki/DMARC

There is a common problem which prevents DMARC from a widespread usage for a strict policy (policy=REJECT): Redirects can destroy the DMARC signature header. This happens with common groupware (Microsoft Exchange, Novell GroupWise,IBM Lotus Domino), with Sieve-rules and some free mail providern (some hotmail.xyz accounts and web.de). If you would use a strict REJECT policy, such addresses with active redirects could bounce your e-mail. The usage of a neutral policy (policy=NONE) has no disadvantages and may even give you some improvements in deliverability.

promio.net will receive generated DMARC reports and plans to establish a DMARC monitor as part of promio.connect. If you send 100% of your e-mails with “example.com”, you can setup DMARC bei registering the following TXT-Record in your DNS for “_dmarc.example.com”:

v=DMARC1; p=none;sp=none; rua=mailto:dmarc@promio.net; ruf=mailto:dmarc@promio.net; pct=100

If you want to receive copies of the DMARC reports to your address “dmarc@client.com”, please change the record to:

v=DMARC1; p=quarantine;sp=none; rua=mailto:dmarc@promio.net,example@vnr.de; ruf=mailto:dmarc@promio.net,dmarc@client.com; pct=100