Follow these steps:

1. Cancel the VA setting Blocking Protected file in Security Risk Scan Action tab:

   

2. Add a special group which includes domain or address mailbox.

   

3. Choose "Enter SMTP Address" for external domain or AD users/groups/contacts, then add the selected accounts depending on internal mailboxes format. Click Save.

   

4. Add a Customized Policy in Attachment Blocking to block protected files which only applies to inbound mails.
   Choose specific sender(s).

   

   Select "Accounts" and choose Anyone. Then select "Exclude Accounts", choose <Special Groups> created from the previous steps. Click Save.

   

5. Choose "Block all password protected office documents and compressed files."

   

6. Choose "Quarantine entire message" and "Notify", under "Select an action".

   

7. Choose "Notify sender."

   

8. Name it then click Save.

   

9. Enable and save the policy.

   

After the above configurations, SMEX will block protected file for inbound emails only and not internal emails. It will also send notification to sender.