Hello guys, I have three questions for you that I am unsure about and hoping that someone at Microsoft will be able to help:
First two questions are related to Mimecast acting as inbound security gateway to O365: 1. When Mimecast acts as inbound gateway solution and it receives an email, it does DMARC checks and lets the email through to O365 environment. Even if an email passes DMARC checks at Mimecast and the email is let through, then O365 also seems to also be doing DMARC checks but both SPF and DKIM fail because of the change that Mimecast does. As a results DMARC fails. My questions is, what is the best practice here in this scenario? Is there a way to turn off DMARC checks at O365? Mimecast suggest that it is whitelisted in O365 but that means that all the spam will be let through as well. 2. Would O365 send DMARC reports back to the sender in the above case? And, if O365 sends DMARC reports back to the sender then emails will be shown as originating from Mimecast but failing DMARC. 3. Would O365 do DMARC checks for internal emails ie. O365 tenant employee to another O365 tenant employee? And would it send DMARC reports in this case?
_______________________________________________ dmarc-discuss mailing list dmarc-discuss@dmarc.org http://www.dmarc.org/mailman/listinfo/dmarc-discuss NOTE: Participating in this list means you agree to the DMARC Note Well terms (http://www.dmarc.org/note_well.html)
