Step 1:Mail relay parameter helps you specify to whom your smtp protocol should forward emails.If this is not configured correctly, spammers might use your mail server.So, make sure to configure the mail relay parameter correctly.
Step 2:Limit the number of connections to your smtp server.To reduce the connection limit, you have to change the total number of connections, the total number of simultaneous connections, the and maximum connection rate for how to Secure email server.
Step 3:Enable the reverse dns lookup feature.This will help to compare the ip address of the sender to both the host and domain names.If it does not match, your smtp mail server will block the messages from the sender.
