On certain machines, you might not have a loopback address assigned. And when trying to use SpamAssassin, it shows this error in /var/log/maillog:

host-foo spamd: spamd: connection from [ip address] at port 55390
spamd: unauthorized connection from [ipaddress]

SpamAssassin usually binds to all the IP addresses on the machine, but you'll need to specify which IP addresses are allowed to be a client. If you have no loopback IPs configured, it detects your IP as a public IP.

You will need to do the following:

- open up /etc/rc.d/atmailserver (or an equivalent)

- find this line:

/usr/local/atmail/spamassassin/bin/spamd -d -x -q -u atmail --virtual-config-dir=/usr/local/atmail/ -m 6 -r /usr/local/atmail/spamassassin/spamd.pid

- change to:

/usr/local/atmail/spamassassin/bin/spamd -A [public IP adddress] -d -x -q -u atmail --virtual-config-dir=/usr/local/atmail/ -m 6 -r /usr/local/atmail/spamassassin/spamd.pid

Where [public IP address] is your IP address.

- restart AtMail:

   % /etc/init.d/atmailserver restart 

If you are using an external MySQL server, and an AtMail installation on an operating system that has SELinux enabled, you might experience the following:

- the installation fails when connecting to the MySQL server
- connecting manually using the mysql command succeeds.

In this case, you need to set SELinux so that it allows HTTP modules to connect to the network. This can be done by executing the following command:

% /usr/sbin/setsebool -P httpd_can_network_connect true 

Retry the installation afterwards.