They should certainly be able to set up DKIM for you, which can't hurt. But not if it's Exchange on prem as it's not supported.
I doubt they will offer to "do DMARC" beyond adding a p=none policy to DNS as that involves dealing with third parties and everything else.
Thanks for your help - having quickly scanned an email authentication white paper from Cisco I have realised I am rapidly getting out of my depth - time to for me to obtain some paid advice me thinks.
My invoice is in the post
@fidbod started
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They should certainly be able to set up DKIM for you, which can't hurt. But not if it's Exchange on prem as it's not supported.
I doubt they will offer to "do DMARC" beyond adding a p=none policy to DNS as that involves dealing with third parties and everything else.