When you plan antivirus scanning for Microsoft Outlook Date files and email messages, you should be aware of potential issues that can arise if certain Outlook files are in use during scanning.
Scanning Outlook files
Outlook Data Files (*.pst) and Offline Folder files (*.ost) are the most frequently-accessed Outlook files. If antivirus perform file-level scanning on them while Outlook is in use, data corruption issues might result.
We recommend that you turn off scanning of Microsoft Outlook Data files:
Go to Filter Management tab from the cloud console.
Click on Edit to modify the policy
Then go to Endpoint à Antivirus
Expand the Detection Settings
Remove the check box next to Detect inside e-mail database
Scanning email messages
We do not recommend that you scan *.pst, *.ost, and other Outlook files directly. Instead, we recommend that you scan email message attachments on the email server and on the Outlook client computer. You may use iSheriff email security which includes antivirus software that was developed to scan incoming and outgoing email messages.