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Troubleshooting common issues in Cloud App Security (CAS)

    • Updated:
    • 19 May 2021
    • Product/Version:
    • Cloud App Security
    • Platform:

This article lists down the most common issues encountered in CAS, and provides the solution for these issues.


Troubleshooting mail related issue usually requires analyzing the raw mail content including mail headers, mail body and attachments. Therefore, directly forwarding the mail in question can't meet the requirement.

Make sure to export the mail samples in *.msg or *.eml format.

Different environment and mail client software have different approach to collect mail samples. The following are some examples:

Collecting mail samples from Outlook Web App

  1. Access Outlook Web App by logging in to
  2. Start a new message.

    New Message

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  3. Click to edit the message in a new window.

    Open in new Window

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  4. Select all emails you would like to download, and then drag the emails to the new message. This will add them as attachments.

    Select Emails

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  5. Click the down arrow on the attachment and download the email message (will be saved in .eml format), or send the message to yourself and then download all attachments (will be saved in .msg format).

    Download samples

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Collecting mail samples in Outlook 2019

  1. Locate and select the mail sample in Outlook, then click File in the menu.

    File menu

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  2. Select Save As, then save the mail in .msg format.

    Save As

Before sending the sample to Trend Micro Technical support, make sure to compress all the samples and use password "virus" to protect the archive.

Skipped users

Usually a user was skipped because CAS encountered some error when scanning his/her email or files. The most seen root cause is that Office365 throttled the API requests. During busy hours, there were too many API requests from CAS to Office 365 in the meantime, so Office365 throttle on API request is triggered.

To confirm if this is the case, please try again during off-hours.

Cannot Render error

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The error usually show up when you accessed the wrong site. For example, your Sharepoint admin site is -, but you accessed

Apps Page

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When provisioning/deprovisioning Office365 Sharepoint, OneDrive or Teams, you are required to access Sharepoint admin site (https://{sharepoint_admin_site}/_layouts/15/TA_AllAppPrincipals.aspx) to add or remove the related apps.

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