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Chapter 2 Mail Service Setup 33
When adding to the list, Server Admin accepts a variety of notations. You can:
Enter a single IP address or the network/netmask pattern, such as 192.168.40.0/21. Â
Enter a host name, such as mail.example.com. Â
Enter an Internet domain name, such as example.com. Â
Rejecting Mail from Blacklisted Senders
Mail service can reject mail from SMTP servers that are blacklisted as open relays by a
Real-time Blacklist (RBL) Server. Mail service uses an RBL server that you specify. RBLs
are sometimes called black-hole servers.
Blocking unsolicited mail from blacklisted senders might not be completely accurate.
Sometimes it prevents valid mail from being received.
To reject mail from blacklisted senders:
1 In Server Admin, select Mail in the Computers & Services pane.
2 Click Settings.
3 Select the Relay tab.
4 Click the “Use these junk mail rejection servers” checkbox.
5 Edit the list of servers by adding the DNS name of an RBL server:
Click the Add (+) button to add a server to the list, then enter the domain name of a Â
RBL server, such as rbl.example.com.
Click the Remove (-) button to delete the selected server from the list. Â
Click the Edit (/) button to change the selected server. Â
Filtering SMTP Connections
You can use Mac OS X Server Firewall service to allow or deny access to your SMTP
Mail service from specic IP addresses. Filtering disallows communication between
an originating host and your mail server. Mail service doesn’t receive the incoming
connection and no SMTP error is generated or sent back to the client.
To lter SMTP connections:
1 In Server Admin, select Firewall in the Computers & Services pane.
2 Create a rewall IP lter using the instructions in Network Services Administration,
using the following settings:
Access: denied Â
Port number: 25 (or your incoming SMTP port, if you use a nonstandard port) Â
Protocol: TCP Â
Source: the IP address or address range you want to block Â
Destination: your mail server’s IP address Â