Configure filter to discard certain email attachments like .tar.gz,vbs, scr ,exe from your cPanel >> User Level Filtering
For example you can discard emails with the attachment .tar.gz with following rule
In cPanel select "User Level Filtering" option present under the "Mail" section.
Select the email address from the emails list and then select "Manage Filters" option.
It will give you new window where you can manage the rules for your email account.
First set the filter rule name in "Filter Name" section and then select the "Body" option present under the "Rules" sections first drop down menu bar and similarly select "Equal" OR "matches regex"option from "Rules" sections second drop down menu bar and add the .tar.gz in third empty box.
Select the "Actions" option as per your requirement from drop down menu bar in this example I have set "Discard Message".
After adding the rules you need to select "Activate" option to activate your filter rule.
########## NOTE AND BE-CAREFUL ##########
Above rule will also applied on incoming emails which contains word in message body like .tar.gz OR similar for any other extensions as well.