After setting the server time with the following command:

dpkg-reconfigure tzdata

The syslog service now needs restarted:

service syslog restart

Tail the mail.log to check the entries are stamped with the correct time:

tail -f /var/log/mail/log

Edit the postfix master.cf:

vim /etc/postfix/master.cf

Uncomment the following lines:

smtps     inet  n       -       -       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING

*leave milter commented.

Now restart postfix for changes to take effect:

/etc/init.d/postfix restart

Add the new domain through the iredadmin panel – hostdomain.com/iredadmin

Server

1. Generate domain keys for the new domain:

amavisd-new genrsa /var/lib/dkim/newdomain.co.uk.pem

2. Edit the amavis conf file:

vim /etc/amavis/conf.d/50-user

Change @local_domains_maps = 1; to:

@local_domains_maps = ['.'];

INSTALL AND CONFIGURE

Install the domain packages:

apt-get install opendkim opendkim-tools

Add the following to /etc/opendkim.conf:

Domain example.com
KeyFile /etc/postfix/dkim.key
Selector dkim
SOCKET inet:8891@localhost

*example.com being your domain

Add the following to /etc/default/opendkim:

SOCKET="inet:8891@localhost"

Add the following to the bottom /etc/postfix/main.cf:

Run the command:

postsuper -d ALL