Fortimail is blocking Calendar responses

[Flash_ITSD]

When you accept or reject a meeting request, with the option to send response to sender, it is actually the exchange server that sends the email,  with the following details:

From: exchangexxxxxxxxATyourtenant.onmicrosoft.com

Header From: your email.
Having DMARC set to reject, this email will have the DMARC failing for not having DKIM signature.
How to allow these kinds of email responses in Fortimail?

[abelio]

Hi

One (of several) approach: define an IP policy with your exchange's sender IP address as source IP, apply on it an antispam profile not checking spf/dmarc/dkim , all the other profiles as you wish.

On that IP policy, check the box "Take precedence over recipient based policy match" to be sure to match this one.