Now edit etc/postfix/header_checks. It should look like this:

/^Received:/ HOLD

chown postfix.postfix /var/spool/MailScanner/incoming

chown postfix.postfix /var/spool/MailScanner/quarantine

mkdir /var/spool/MailScanner/spamassassin

chown postfix.postfix /var/spool/MailScanner/spamassassin

Now edit /etc/MailScanner/MailScanner.conf and set the following lines as shown:

Run As User = postfix
Run As Group = postfix
Queue Scan Interval = 120
Incoming Queue Dir = /var/spool/postfix/hold
Outgoing Queue Dir = /var/spool/postfix/incoming
MTA = postfix
Virus Scanners = clamav
SpamAssassin User State Dir = /var/spool/MailScanner/spamassassin

Now configure sasl authentication.

mkdir -p /var/spool/postfix/var/run/saslauthd

Now we have to edit /etc/default/saslauthd. It should look like this:

# This needs to be uncommented before saslauthd will be run automatically
START=yes
PARAMS="-m /var/spool/postfix/var/run/saslauthd -r"
# You must specify the authentication mechanisms you wish to use.
# This defaults to "pam" for PAM support, but may also include
# "shadow" or "sasldb", like this:
# MECHANISMS="pam shadow"
MECHANISMS="pam"