For G Suite.
For Office 365.
Is there any naming rule for the generated Password Protected Zip file when attaching multiple files on one mail?
The name of the encryption objective file which first appears after the mail source analysis is to be used as the ZIP file name.
Please note that:
The structure of the mail generated after the mail source analysis (file appearance order) depends on your using mail client environment.
Consequently, this appearance order should not be explicitly specified.