Hi!

Do we have to enter all the IP Addresses in our firewall to be able to connect to Office 365 or FQDNs are only needed as per this document?

https://support.office.com/en-us/article/Office-365-URLs-and-IP-address-ranges-8548a211-3fe7-47cb-abb1-355ea5aa88a2

Thanks.

It depends on how your firewall is filtering.

Hi,

I noticed that the issue is related to Exchange Online. If you still have any question about Office 365 configuration, please ask a question in Exchange Online forum for more help:

https://social.technet.microsoft.com/Forums/msonline/en-US/home?forum=onlineservicesexchange

Regards,