I saw this post over on the Fortinet Support forums and wanted to cross post it here in case no one has experienced this issue. Always check the web filter and make sure domains are rated properly! Some situations it makes sense to allow websites if they are unrated or if a rating failure occurs. Especially in environments where down time hurts. Granted, I like to keep my environment more secure than that so it just makes sense for me to be quick with the troubleshooting.

Question: Hi all,

I am trying to get Office 365 to work on site behind a Fortigate 50E. Unfortunately I’m having a lot of trouble.

I found this document: http://cookbook.fortinet.com/exempting-google-ssl-inspection/

I was able to translate that into 5.4 and create the addresses that should be used by Office 365, but it still isn’t working. When I look at the IP4 policy, it appears to just be doing SSL Certificate Inspection. Do the exceptions I put into the Deep Inspection apply to SSL Certificate Inspection as well? Because that is very not clear. And if not, how do I exempt sites from SSL Certificate Inspection?

Thanks!

Correct Answer: This was actually being blocked in Webfiltering because the autodiscover.domain.com was unrated, which was set to block by default. I created an exception for it and changed the category from unrated to business IT use, and it now works.

Thanks!