To disable VRFY on IMSVA:

1. Log in to your IMSVA box using root.
2. Go to /opt/trend/imss/postfix/etc/postfix directory.
3. Edit the main.cf file.
4. Add the following line at the bottom of the file then save the changes:

   disable_vrfy_command = yes

5. Reload postfix using the following command:

   postfix reload

6. Verify if configuration is active using the following command:

   postconf | grep -i vrfy

   The result should be:

   [root@imsva postfix]# postconf | grep -i vrfy
   disable_vrfy_command = yes
   [root@imsva postfix]#