For G Suite.
For Office 365.
Is there any method to view compressed file (such as ZIP) attached to e-mail via HDE Secure Browser?
When you open attached file of e-mail on HDE Secure Browser, it displays content by using view function of GoogleDrive.
Thus, you can view general business documents (such as Word, Excel files and the like) or compressed those documents without passwords, but you can't view or unpack files compressed with password. (Besides, files which need passwords are also applicable to this case.)
The purpose of HDE Secure Browser is to prevent downloading files to the device, so you can't download attached files to your device.