How to block all Webmails

[olivier_adm]

Dear Fortinet community,

I am having an issue with what it seems a simple configuration on my Fortigate, and I hope someone could help me figure it out. The Fortigate is full licenced and up to date (not yet in v7 though).

I need to block all Webmails from my LAN, but still let Outlook 365 working properly.

So far I have tried severals settings on the Fortigate, but it remains unsuccessful :

-          I Blocked the category "Webmail" in WebFilter. It works quite well, even too much as it disconnects O365 via Outlook. I tracked all the websites blocked by this UTM, but there are always some new which make impossible to manage.

-          So I tried to set up Application Control. It works for some Webmails such as Gmail and our O365 works too. But unfortunately others Webmails like Free,SFR,Orange whose use HTTP browser are not checked by this parameter so they are not blocked.

Would you have any idea how could I block all Webmails without disturbing our O365 mails please ?

Have a great day,

Olivier