Combell (previously Openminds.be) is DMARC-compliant via SPF and DKIM.
Contact Combell support for DKIM configuration.
If you're a Basic E-mail user, the recommended value is: 'include:_spf.relay.mailprotect.be'. If you're an Exchange Email user, the value to add to your SPF is: 'include:_spf.powermail.be'. For more information, visit: https://www.combell.com/nl/help/kb/wat-is-een-spf-record-hoe-kan-ik-een-spf-record-toevoegen/