This source is known to forward email
forwarding notes:This is a large hosting provider, so large volumes of email may appear to be forwarded thru the environment via various hosted subscribers. If any given traffic should appear as original rather than forwarded, it should pass SPF authentication in alignment in order for that classification to be made. For messages whose domain is hosted at the provider, they may also be slotted as original.
This large hosting provider is capable of sending DMARC compliant messages for its subscribers, via both DKIM and SPF authentication. If your domain is hosted here, see subscriber documentation or contact the vendor support for specifics.
Contact vendor for DKIM setup.
Contact vendor for SPF setup.