Relay restrictions Here you can specify which mail servers are allowed to send out mail via Mail essentials. Of course you will need to add the IP of your mail server and your local domain. This way, any mail from a mail server that is not listed here will be bounced. By default, only mail for the local domain will be sent, to protect you from spammers using your mail server to send spam mail. To add domains that can send out mail via mail essentials; 1. Click Add 2. Enter a mail domain, i.e. gfi.com and then optionally enter an IP of the mail server name that may relay mail. If you are not sure what the IP of the machine is, open a DOS box and type: ping <machine name>, where machine name is the name of your mail server. Ping will reply with the correct IP.