Specific file extension block in postfix :

How to block attachment file extension in Postfix (OS= Debian)

Step 1. Add the following line on main.cf

# vim /etc/postfix/main.cf

mime_header_checks = regexp:/etc/postfix/mime_header_checks

:wq!                 Save and close the file.

Step 2. Add following line on /etc/postfix/mime_header_checksfile:

# vim /etc/postfix/mime_header_checks

 /name=[^>]*\.(bat|exe|dll|eml|vbs)/ REJECT    ### File ext that you want to block ####

:wq!                 Save and close the file.



3. Restart Postfix service and check with mail log.

/etc/init.d/postfix restart

Check with mail log

tail -f /var/log/mail.log