diff --git a/install_roundcube.sh b/install_roundcube.sh
index 395c529..6c418d2 100755
--- a/install_roundcube.sh
+++ b/install_roundcube.sh
@@ -191,8 +191,12 @@ MAIN_DOMAIN=${_tmp_string##*.}
 
 [[ -n "$ROUNDCUBE_TMPDIR" ]] || ROUNDCUBE_TMPDIR="$DEFAULT_ROUNDCUBE_TMPDIR"
 
-[[ -n "$IPV4" ]] || fatal  "IPv4 Address (IPV4) not present!" 
-[[ -n "$IPV6" ]] || fatal  "IPv4 Address (IPV6) not present!" 
+if [[ -z "$IPV4" ]] && [[ -z "$IPV6" ]] ; then
+   fatal "Neither an IPv4 nor an IPv6 address are given.!"
+else
+   [[ -n "$IPV4" ]] || warn  "IPv4 Address not present!" 
+   [[ -n "$IPV6" ]] || warn  "IPv6 Address not present!" 
+fi
 
 [[ -n "$APACHE_DEBIAN_INSTALLATION" ]] || APACHE_DEBIAN_INSTALLATION=false
 [[ -n "$PHP_DEBIAN_INSTALLATION" ]] || PHP_DEBIAN_INSTALLATION=false
@@ -1221,10 +1225,26 @@ fi
 
 echononl "\tCreate VHost Configuration '${WEBSITE_NAME}.conf'.."
 _failed=false
-cat <<EOF > ${APACHE_VHOST_DIR}/${WEBSITE_NAME}.conf 2>> $log_file
+_create_vhost_config=true
+if [[ -n "$IPV6" ]] && [[ -n "$IPV4" ]] ; then
+   _vhost_ip_string_80="$IPV4:80 [$IPV6]:80"
+   _vhost_ip_string_443="$IPV4:443 [$IPV6]:443"
+elif [[ -n "$IPV4" ]] ; then
+   _vhost_ip_string_80="$IPV4:80"
+   _vhost_ip_string_443="$IPV4:443"
+elif [[ -n "$IPV6" ]] ; then
+   _vhost_ip_string_80=" [$IPV6]:80"
+   _vhost_ip_string_443=" [$IPV6]:443"
+else
+   echo_failed
+   error "Neither an ipv4 nor an ipv6 address are given.!"
+   _create_vhost_config=false
+fi
+if $_create_vhost_config ; then
+   cat <<EOF > ${APACHE_VHOST_DIR}/${WEBSITE_NAME}.conf 2>> $log_file
 # -- $WEBSITE_NAME -- #
 
-<VirtualHost $IPV4:80 [$IPV6]:80>
+<VirtualHost ${_vhost_ip_string_80}:80>
 
    ServerAdmin $WEBMASTER_EMAIL
 
@@ -1240,7 +1260,7 @@ cat <<EOF > ${APACHE_VHOST_DIR}/${WEBSITE_NAME}.conf 2>> $log_file
 </VirtualHost>
 
 
-<VirtualHost $IPV4:443 [$IPV6]:443>
+<VirtualHost ${_vhost_ip_string_443}:443>
 
    ServerAdmin $WEBMASTER_EMAIL