Summary
The VRFY clause is a method of verifying the existence of a user on a mail server.
You can either verify the existence of particular user or use a wildcard verify (VRFY *) to ask the server to return the complete list of users.
On IMSVA version 8.2, VRFY is disabled by default but not on lower versions. The wildcard option (VRFY *) can be exploited by spammers to bulk harvest email addresses so it is necessary that you disable this clause.
Details
To disable VRFY on IMSVA:
- Log in to your IMSVA box using root.
- Go to /opt/trend/imss/postfix/etc/postfix directory.
- Edit the main.cf file.
- Add the following line at the bottom of the file then save the changes:
disable_vrfy_command = yes
- Reload postfix using the following command:
postfix reload
- 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]#
