How to block attachments by file extension in SmarterMail v16x

Log in as the System Administrator

Go to the Settings area

Click on General Settings

Look for the Attachments card: here you'll have editable areas for both Incoming Extension Blacklist and Outgoing Extension Blacklist.

Click on whichever you want to edit and add your extensions: BIN, ZIP, EXE...one item per line.

Save your changes.