Apple Mac OS X Server (version 10.2.3 or later) - Manual (Page 425)

Mail Service 425
Allowing SMTP Relay for a Backup Mail Server
If your network has more than one mail server, one can be designated as a backup server to
deliver mail in case the primary server goes down. (Backup mail servers are designated by
MX records.) A backup mail server may need to relay SMTP mail. You can set your server to
ignore SMTP relay restrictions when accepting mail as a backup server for another mail
server.
To allow SMTP relay for a backup mail server:
1 In Server Settings, click the Internet tab.
2 Click Mail Service and choose Configure Mail Service.
3 Click the Protocols tab and choose Apple Mail Service SMTP from the pop-up menu.
4 Click SMTP Options.
5 Select “SMTP relay when host is a backup for destination” and click Save.
Filtering SMTP Connections
You can use the firewall service of Mac OS X Server to allow or deny access to your SMTP
mail service from specific IP addresses.
1 In Server Settings, click the Network tab.
2 Click Firewall and choose Show Firewall List.
3 Click New and configure the settings to create a filter that allows or denies access to port
number 25 from an IP address or range of IP addresses that you specify, then click Save.
If your SMTP service does not use port 25, which is standard for incoming SMTP mail, enter
your incoming SMTP port number instead.
4 Add more new filters for the SMTP port to allow or deny access from other IP addresses or
address ranges.
For additional information on the firewall service, see Chapter 15, “Firewall Service.”
Working With Undeliverable Mail
Mail messages may be undeliverable for several reasons. You can configure your mail service
to forward undeliverable incoming mail, limit attempts to deliver problematic outgoing mail,
and report failed delivery attempts. Incoming mail may be undeliverable because it has a
misspelled address or is addressed to a deleted user account. Outgoing mail may be
undeliverable because it’s misaddressed or the destination mail server is not working.
LL0395.Book Page 425 Wednesday, November 20, 2002 11:44 AM