This indicates an attack attempt to exploit an Information Spoofing vulnerability in in Microsoft Outlook.
The vulnerability is due to an error when the vulnerable software attempts to handles maliciously crafted email. An attacker can exploit this by tricking a user into opening a crafted email and redirect the user to another site, leading to further attacks.
Microsoft Office for Mac 2011
Microsoft Office 2016 for Mac
Information Spoofing: Remote attackers can serve spoof contents to unsuspecting targets.
Apply the most recent upgrade or patch from the vendor.