Step 3: Specify the
Hosts That You Want to Openly Relay to
All Domains
Note:
Anyone can send to the domains that you
specified in Step 2.
This step is for hosts, which are most
likely your internal servers that would
need to send to all domains on the
Internet. It is not recommended to not
have any restrictions because anyone can
use your server as an open relay. It is
recommended to only allow the minimum,
necessary hosts to openly relay to all
domains. To do so:
-
Open
the properties of the Default SMTP
Virtual Server.
-
On the
Access tab, click Relay.
-
Click
Only the list below, click Add, and
then add the hosts that need to use
this SMTP host to send e-mail.
On the
dialog box that appears, you have
the following options:
-
Single computer: Specify one
particular host that you want to
relay off of this server. If you
click the DNS Lookup button, you
can lookup an IP address of a
specific host.
-
Group of computers: Specify a
base IP address for the
computers that you want to
relay. You have to specify the
octets in the IP address for
hosts that you will allow to
relay. For example: If the IP
address is 192.68.7.21, and you
want any hosts with the first
two octets 192.68 to relay,
specify 255.255.0.0 for the
subnet mask.
-
Domain: Select all of the
computers in a domain by domain
name that will openly relay.
This option adds processing
overhead, and might reduce the
SMTP service performance because
it includes reverse DNS lookups
on all IP addresses that try to
relay to verify their domain
name.
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