Now make squirrelmail talk your language. If you only use English you can skip the last line in the file of course.

Edit /var/lib/locales/supported.d/local.

It should look like this: (if you are Dutch, otherwise adjust as desired).
Main thing is to enable your locale with the charset ISO-8859-1.

en_US.UTF-8 UTF-8
nl_NL.UTF-8 UTF-8
en_US.ISO-8859-1	ISO-8859-1
nl_NL.ISO-8859-1	ISO-8859-1

dpkg-reconfigure locales

Now make sure that the DirectoryIndex line in /etc/apache2/apache2.conf reads:

DirectoryIndex index.html index.htm index.shtml index.cgi index.php index.php3 index.pl index.xhtml

Edit /etc/apache2/ports.conf and add Listen 443:

Listen 80
Listen 443

Now we configure Postfix and MailScanner.

postconf -e 'mynetworks = 127.0.0.0/8, 192.168.1.0/24'

postconf -e 'smtpd_sasl_local_domain ='

postconf -e 'smtpd_sasl_auth_enable = yes'

postconf -e 'smtpd_sasl_security_options = noanonymous'

postconf -e 'broken_sasl_auth_clients = yes'

postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks,reject_unauth_destination'

postconf -e 'inet_interfaces = all'

echo 'pwcheck_method: saslauthd' >> /etc/postfix/sasl/smtpd.conf

echo 'mech_list: plain login' >> /etc/postfix/sasl/smtpd.conf

postconf -e 'smtpd_tls_auth_only = no'

postconf -e 'smtp_use_tls = yes'

postconf -e 'smtpd_use_tls = yes'

postconf -e 'smtp_tls_note_starttls_offer = yes'

postconf -e 'smtpd_tls_key_file = /etc/apache2/ssl/apache.pem'

postconf -e 'smtpd_tls_cert_file = /etc/apache2/ssl/apache.pem'

postconf -e 'smtpd_tls_loglevel = 1'

postconf -e 'smtpd_tls_received_header = yes'

postconf -e 'smtpd_tls_session_cache_timeout = 3600s'

postconf -e 'tls_random_source = dev:/dev/urandom'

postconf -e 'home_mailbox = Maildir/'

postconf -e 'mailbox_command ='

postconf -e 'header_checks = regexp:/etc/postfix/header_checks'

postconf -e 'relayhost ='

postconf -e 'virtual_alias_domains = hash:/etc/postfix/virtual'

postconf -e 'virtual_alias_maps = hash:/etc/postfix/virtual'

touch /etc/postfix/header_checks

touch /etc/postfix/virtual