This method will introduce a VBA, and then create a rule with this VBA script to block all emails with .zip attachments in Outlook automatically. Please do as follows:

1. In Outlook, press Alt + F11 keys together to open the Microsoft Visual Basic for Applications window.

2. Click Insert > Module, and then paste below VBA code into the new Module window.

VBA: Move emails with .zip attachments to Junk E-mail folder

Dim I As Long
'Check each attachment
For I = 1 To Item.Attachments.Count
'If the attachment's file name ends with .zip
If Right(UCase(Item.Attachments.Item(I).FileName), 4) = ".ZIP" Then
'Move the message to Junk E-mail
Item.Move Application.Session.GetDefaultFolder(olFolderJunk)
'No need to check any of this message's remaining attachments
Exit For
End If
Next I
End Sub

3. Save the VBA code, and close the Microsoft Visual Basic for Applications window.

4. Now you return to the Outlook main interface. Select any email in the specified email account, and click Home > Rules > Manage Rules & Alerts. See screenshot:

5. In the Rules and Alerts dialog box, please click the New Rule under E-mail Rules tab. See screenshot:

6. Now the Rules Wizard opens. Please click the Apply rule on messages I receive option and click the Next button. See screenshot:

7. In the Rules Wizard (Select condition(s)), please check which has an attachment option, and click the Next button. See screenshot:

8. In the Rules Wizard (Select action(s)), please do as following screenshot shown:
(1) Check the run a script option;
(2) Click the text of a script in the Step 2 section;
(3) In the Select Script dialog box select the new added VBA script, and click OK button;
(4) Click the Next button.

9. Click Next button in the Rules Wizard (select exceptions) directly.

10. Now in the last Rules Wizard, please (1) name the new rule in the Step 1 box, (2) specify options as you need in the Step 2 section, and then (3) click the Finish button. See screenshot:

11. Close the Rules and Alerts dialog box.

So far, you have finished the rule with the specified VBA script. And all incoming emails with .zip attachments will be moved to the Junk E-mail folder automatically.

Prevent Outlook from blocking attachments

Delete blocked attachments from emails in Outlook