How to allow mail relay of specific IP address

Stev · 02-12-2004, 04:16 PM

I have set up an anti-spam relay server (RH Linux 8 postfix, amavis, spamAssassin) between my mail server and the Internet. As such, I have enabled relaying from my mail server only in order to avoid becoming an open relay. However, I have an off-site server farm that sends email messages to acknowledge receipt of submissions. These of course fail because I don't allow relaying. So my clients don't get their confirmations. My question is, can I configure a specific public IP address to allow relaying from or will this create an open relay? My CIO says that it will not but I'm not convinced and my tail is on the line if I open one up. I can't use pop before smtp because this process doesn't check for mail.

Can anybody point me in the right direction?

Thanks

chort · 02-12-2004, 09:06 PM

Have you looked in the /etc/postfix/main.cf file at all?

Quote:

# TRUST AND RELAY CONTROL

# The mynetworks parameter specifies the list of "trusted" SMTP
# clients that have more privileges than "strangers".
#
# In particular, "trusted" SMTP clients are allowed to relay mail
# through Postfix. See the smtpd_recipient_restrictions parameter
# in file sample-smtpd.cf.
#
# You can specify the list of "trusted" network addresses by hand
# or you can let Postfix do it for you (which is the default).
#
# By default (mynetworks_style = subnet), Postfix "trusts" SMTP
# clients in the same IP subnetworks as the local machine.
# On Linux, this does works correctly only with interfaces specified
# with the "ifconfig" command.
#
# Specify "mynetworks_style = class" when Postfix should "trust" SMTP
# clients in the same IP class A/B/C networks as the local machine.
# Don't do this with a dialup site - it would cause Postfix to "trust"
# your entire provider's network. Instead, specify an explicit
# mynetworks list by hand, as described below.
#
# Specify "mynetworks_style = host" when Postfix should "trust"
# only the local machine.
#
#mynetworks_style = class
#mynetworks_style = subnet
#mynetworks_style = host

# Alternatively, you can specify the mynetworks list by hand, in
# which case Postfix ignores the mynetworks_style setting.
#
# Specify an explicit list of network/netmask patterns, where the
# mask specifies the number of bits in the network part of a host
# address.
#
# You can also specify the absolute pathname of a pattern file instead
# of listing the patterns here. Specify type:table for table-based lookups
# (the value on the table right-hand side is not used).
#
#mynetworks = 168.100.189.0/28, 127.0.0.0/8
#mynetworks = $config_directory/mynetworks
#mynetworks = hash:/usr/local/etc/postfix/network_table

linuxxed · 02-13-2004, 06:40 AM

I would ask you to take a look at the SMTP AUTH mechanisms before using "POP before SMTP". I use sendmail but I don't believe you can't do that on Postfix.

IP based Relaying can be done on any good mail server.

I personally use SMTP with TLS and PLAIN/LOGIN as AUTH.