Upon checking the mail tracking logs, you find out that your email was deleted by the High-Risk Attachment rule of Hosted Email Security (HES).
Examples of a high-risk attachment could be an executable file with .exe extension or a media file (.mp3) that has been renamed to harmless_file.txt. If a message is identified as containing a high-risk attachment based on the criteria defined in the rule, then the attachment will be deleted from the email.
This article shows you how to stop the rule from deleting what you consider a legitimate mail.
As a workaround to the High-Risk Attachment rule, you can do any of the following options:
- Log on to the HES console.
- Click Inbound Protection tab then Policy.
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Under Rules status, look for "High-risk attachment" and under the Status column, click the Check icon.
The said icon will now become an x-mark. This means that the rule has been disabled.
You may do the same procedure to the Outbound High-risk attachment rule if you want to.
- Log on to the HES console.
- Click Inbound Protection tab then Policy.
- Select the High-Risk Attachment rule.
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Go to Recipients and Senders > Recipient Exceptions.
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Enter the email address or the domain of the sender on the textbox and click Add.
The email addresses or the domains will be added to the Selected column.
- Click Save.
- Log on to the HES console.
- Click Inbound Protection tab then Policy.
- Select the High-Risk Attachment rule.
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Go to Scanning Criteria > Advanced.
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Go to the selected "Attachment is" checkbox then click name or extension. The Attachment Names window will appear.
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Tick the checkbox next to File extensions to block (recommended). A list of extensions will be shown.
- Uncheck all the extensions you want to be excluded from scanning.
- Click Save.
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Go back to Advanced section then navigate to the selected "Attachment is" checkbox then click MIME content-type. The Attachment MIME Type window will appear.
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Uncheck all the MIME types you want to be excluded.
- Go back to Advanced section then navigate to the selected "Attachment is" checkbox then click true file type. The Attachment True File Type window will appear.
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Uncheck all the file types you want to be excluded.
- Click Save.
