diff --git a/postinstall b/postinstall
index c20d1fd..1225ab6 100755
--- a/postinstall
+++ b/postinstall
@@ -181,7 +181,7 @@ select_subscription(){
 }
 
 ask_locales(){
-    locales=$(whiptail --title "SET LOCALES" --backtitle "$PROG" --inputbox "Please enter a space separated list of locales to generate." 9 76 "$(echo $(grep -vE '#|^$' /etc/locale.gen | cut -d ' ' -f1))" 3>&1 1>&2 2>&3)
+    if ! locales=$(whiptail --title "SET LOCALES" --backtitle "$PROG" --inputbox "Please enter a space separated list of locales to generate." 9 76 "$(echo $(grep -vE '#|^$' /etc/locale.gen | cut -d ' ' -f1))" 3>&1 1>&2 2>&3); then cancel_dialog ; fi
 }
 
 ask_ssh_hardening(){
@@ -379,16 +379,22 @@ harden_ssh(){
 ask_mail_config(){
     mailconfig=0
     smtpauth=0
+    senderaddress=""
+    displayname=""
+    recipientaddress=""
+    smtphost=""
+    smtpport=25
+    username=""
     if whiptail --title "MAIL DELIVERY" \
     --backtitle "$PROG" \
     --yes-button "MAIL CONFIG" \
     --no-button "SKIP" \
     --yesno "Do you want to configure postfix with a smarthost?" 9 76 ; then
         mailconfig=1
-        senderaddress=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter your sender email address." 9 76 3>&1 1>&2 2>&3)
-        displayname=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter your sender display name." 9 76 3>&1 1>&2 2>&3)
-        recipientaddress=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the email address to receive notifications." 9 76 3>&1 1>&2 2>&3)
-        smtphost=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the servername of your smarthost." 9 76 3>&1 1>&2 2>&3)
+        if ! senderaddress=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter your sender email address." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
+        if ! displayname=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter your sender display name." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
+        if !recipientaddress=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the email address to receive notifications." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
+        if ! smtphost=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the servername of your smarthost." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
         smtpport=$(inputbox_int 'MAIL DELIVERY' 'Please enter the port of your smarthost' 7 25)
         if whiptail --title "MAIL DELIVERY" \
         --backtitle "$PROG" \
@@ -396,8 +402,8 @@ ask_mail_config(){
         --no-button "SKIP" \
         --yesno "Do you want to configure authentication against your smarthost?" 9 76 ; then
             smtpauth=1
-            username=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the username for authentication." 9 76 3>&1 1>&2 2>&3)
-            password=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --passwordbox "Please enter the passsword for authentication." 9 76 3>&1 1>&2 2>&3)
+            if ! username=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --inputbox "Please enter the username for authentication." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
+            if ! password=$(whiptail  --title "MAIL DELIVERY" --backtitle "$PROG" --passwordbox "Please enter the passsword for authentication." 9 76 3>&1 1>&2 2>&3); then cancel_dialog; fi
         fi
     fi
 }
@@ -548,6 +554,14 @@ summary(){
     suppress subscription warning: $suppress_warning\n\
     auto-snapshot: $autosnap\n\
     ssh-hardening: $ssh_hardening\n\
+    mail delivery: $mailconfig
+    sender email: $senderaddress
+    sender display name: $displayname
+    notification address: $recipientaddress
+    smarthost: $smtphost
+    smarthost port: $smtpport
+    smarthost auth: $smtpauth
+    smarthost username: $username
     " 30 76 ; then
         installation_task
     else
diff --git a/proxmox-zfs-postinstall.sh b/proxmox-zfs-postinstall.sh
deleted file mode 100644
index 8ff9246..0000000
--- a/proxmox-zfs-postinstall.sh
+++ /dev/null
@@ -1,312 +0,0 @@
-#!/bin/bash
-
-###### CONFIG SECTION ######
-
-# Define basic tools to install
-TOOLS="sudo vim ifupdown2 libpve-network-perl net-tools dnsutils ethtool git curl unzip screen tmux iftop lshw smartmontools nvme-cli lsscsi sysstat zfs-auto-snapshot htop mc rpl lsb-release"
-
-#### PVE CONF BACKUP CONFIGURATION ####
-
-# Define target dataset for backup of /etc
-# IMPORTANT NOTE: Don't type in the leading /, this will be set where needed
-PVE_CONF_BACKUP_TARGET=rpool/pveconf
-
-# Define timer for your backup cronjob (default: every 15 minutes from 3 through 59)
-PVE_CONF_BACKUP_CRON_TIMER="3,18,33,48 * * * *"
-
-# Get Debian version info
-source /etc/os-release
-
-###### SYSTEM INFO AND INTERACTIVE CONFIGURATION SECTION ######
-
-ROUND_FACTOR=512
-
-roundup(){
-    echo $(((($1 + $ROUND_FACTOR) / $ROUND_FACTOR) * $ROUND_FACTOR))
-}
-
-roundoff(){
-    echo $((($1 / $ROUND_FACTOR) * $ROUND_FACTOR))
-}
-
-#### L1ARC SIZE CONFIGURATION ####
-
-# get total size of all zpools
-ZPOOL_SIZE_SUM_BYTES=0
-for line in $(zpool list -o size -Hp); do ZPOOL_SIZE_SUM_BYTES=$(($ZPOOL_SIZE_SUM_BYTES+$line)); done
-
-# get information about available ram
-MEM_TOTAL_BYTES=$(($(awk '/MemTotal/ {print $2}' /proc/meminfo) * 1024))
-
-# get values if defaults are set
-ARC_MAX_DEFAULT_BYTES=$(($MEM_TOTAL_BYTES / 2))
-ARC_MIN_DEFAULT_BYTES=$(($MEM_TOTAL_BYTES / 32))
-
-# get current settings
-ARC_MIN_CUR_BYTES=$(cat /sys/module/zfs/parameters/zfs_arc_min)
-ARC_MAX_CUR_BYTES=$(cat /sys/module/zfs/parameters/zfs_arc_max)
-
-# calculate suggested l1arc sice
-ZFS_ARC_MIN_MEGABYTES=$(roundoff $(($ZPOOL_SIZE_SUM_BYTES / 2048 / 1024 / 1024)))
-ZFS_ARC_MAX_MEGABYTES=$(roundup $(($ZPOOL_SIZE_SUM_BYTES / 1024 / 1024 / 1024)))
-
-echo -e "######## CONFIGURE ZFS L1ARC SIZE ########\n"
-echo "System Summary:"
-echo -e "\tSystem Memory:\t\t$(($MEM_TOTAL_BYTES / 1024 / 1024))\tMB"
-echo -e "\tZpool size (sum):\t$(($ZPOOL_SIZE_SUM_BYTES / 1024 / 1024))\tMB"
-echo -e "Calculated l1arc if set to defaults:"
-if [ $ARC_MIN_DEFAULT_BYTES -lt 33554432 ]; then
-    echo -e "\tDefault zfs_arc_min:\t32\tMB"
-else
-    echo -e "\tDefault zfs_arc_min:\t$(($ARC_MIN_DEFAULT_BYTES / 1024 / 1024))\tMB"
-fi
-echo -e "\tDefault zfs_arc_max:\t$(($ARC_MAX_DEFAULT_BYTES / 1024 / 1024))\tMB"
-echo -e "Current l1arc configuration:"
-if [ $ARC_MIN_CUR_BYTES -gt 0 ]; then
-    echo -e "\tCurrent zfs_arc_min:\t$(($ARC_MIN_CUR_BYTES / 1024 / 1024))\tMB"
-else
-    echo -e "\tCurrent zfs_arc_min:\t0"
-fi
-if [ $ARC_MAX_CUR_BYTES -gt 0 ]; then
-    echo -e "\tCurrent zfs_arc_max:\t$(($ARC_MAX_CUR_BYTES / 1024 / 1024))\tMB"
-else
-    echo -e "\tCurrent zfs_arc_max:\t0"
-fi
-echo -e "Note: If your current values are 0, the calculated values above will apply."
-echo ""
-echo -e "The l1arc cache will be set relative to the size (sum) of your zpools by policy"
-echo -e "zfs_arc_min:\t\t\t$(($ZFS_ARC_MIN_MEGABYTES))\tMB\t\t= 512 MB RAM per 1 TB ZFS storage (round off in 512 MB steps)"
-echo -e "zfs_arc_max:\t\t\t$(($ZFS_ARC_MAX_MEGABYTES))\tMB\t\t= 1 GB RAM per 1 TB ZFS storage (round up in 512 MB steps)"
-echo ""
-RESULT=not_set
-while [ "$(echo $RESULT | awk '{print tolower($0)}')" != "y" ] && [ "$(echo $RESULT | awk '{print tolower($0)}')" != "n" ] && [ "$(echo $RESULT | awk '{print tolower($0)}')" != "" ]; do
-    read -p "If you want to apply the values by script policy type 'y', type 'n' to adjust the values yourself [Y/n]? "
-    RESULT=${REPLY}
-done
-if [[ "$(echo $RESULT | awk '{print tolower($0)}')" == "n" ]]; then
-    read -p "Please type in the desired value in MB for 'zfs_arc_min' [$(($ZFS_ARC_MIN_MEGABYTES))]: "
-    if [[ ${REPLY} -gt 0 ]]; then
-        ZFS_ARC_MIN_MEGABYTES=$((${REPLY}))
-    fi
-    read -p "Please type in the desired value in MB for 'zfs_arc_max' [$(($ZFS_ARC_MAX_MEGABYTES))]: "
-    if [[ ${REPLY} -gt 0 ]]; then
-        ZFS_ARC_MAX_MEGABYTES=$((${REPLY}))
-    fi
-fi
-
-#### SWAPPINESS ####
-
-echo -e "######## CONFIGURE SWAPPINESS ########\n"
-SWAPPINESS=$(cat /proc/sys/vm/swappiness)
-echo "The current swappiness is configured to '$SWAPPINESS %' of free memory until using swap."
-read -p "If you want to change the swappiness, please type in the percentage as number (0 = disabled):" user_input
-if echo "$user_input" | grep -qE '^[0-9]+$'; then
-    echo "Changing swappiness from '$SWAPPINESS %' to '$user_input %'"
-    SWAPPINESS=$user_input
-else
-    echo "No input - swappiness unchanged at '$SWAPPINESS %'."
-fi
-
-#### ZFS AUTO SNAPSHOT CONFIGURATION ####
-
-# get information about zfs-auto-snapshot and ask for snapshot retention
-declare -A auto_snap_keep=( ["frequent"]="8" ["hourly"]="48" ["daily"]="31" ["weekly"]="8" ["monthly"]="3" )
-dpkg -l zfs-auto-snapshot > /dev/null
-
-if [ $? -eq 0 ]; then
-    echo "'zfs-auto-snapshot' already installed. Reading config..."
-    for interval in "${!auto_snap_keep[@]}"; do
-        if [[ "$interval" == "frequent" ]]; then
-            auto_snap_keep[$interval]=$(cat /etc/cron.d/zfs-auto-snapshot | grep keep | cut -d' ' -f19 | cut -d '=' -f2)
-        else
-            auto_snap_keep[$interval]=$(cat /etc/cron.$interval/zfs-auto-snapshot | grep keep | cut -d' ' -f6 | cut -d'=' -f2)
-        fi
-    done
-else
-    echo "'zfs-auto-snapshot' not installed yet, using script defaults..."
-fi
-echo -e "######## CONFIGURE ZFS AUTO SNAPSHOT ########\n"
-for interval in "${!auto_snap_keep[@]}"; do
-    read -p "Please set how many $interval snapshots to keep (current: keep=${auto_snap_keep[$interval]})" user_input
-    if echo "$user_input" | grep -qE '^[0-9]+$'; then
-        echo "Changing $interval from ${auto_snap_keep[$interval]} to $user_input"
-        auto_snap_keep[$interval]=$user_input
-    else
-        echo "No input - $interval unchanged at ${auto_snap_keep[$interval]}."
-    fi
-done
-
-#### CHECKMK AGENT CONFIGURATION ####
-read -p "Do you want to install checkmk agent on this machine? [y/N] " install_checkmk
-if [[ "$install_checkmk" == "y" ]]; then
-    read -p "Please specify the base url to your checkmk server (e.g. https://check.zmb.rocks/bashclub): " cmk_agent_url
-    read -p "Enable agent encryption (requires setup of Agent Encryption on your checkmk instance). Do you want to activate agent encryption? [y/N] " cmk_encrypt
-    if [[ "$cmk_encrypt" == "y" ]]; then
-        read -p "Please enter the encryption passphrase: " cmk_enc_pass
-    fi
-    read -p "Register your machine on your checkmk server (requires preconfigured automation secret)? [y/N] " cmk_register
-    if [[ "$cmk_register" == "y" ]]; then
-        read -p "Please enter your automation secret: " cmk_secret
-        read -p "Please enter the folder where to store the host: " cmk_folder
-        cmk_site=$(echo $cmk_agent_url | cut -d'/' -f4)
-        read -p "Please enter the checkmk site name: [$cmk_site]" user_input
-        if [[ $(echo -n "$user_input") != "" ]]; then
-            cmk_site=$user_input
-        fi
-        echo "Please select which agent ip address to register:"
-        select ip in $(ip a | grep "inet " | cut -d ' ' -f6 | cut -d/ -f1); do
-            cmk_reg_ip=$ip
-            break
-        done
-    fi
-fi
-
-
-###### INSTALLER SECTION ######
-
-# disable pve-enterprise repo and add pve-no-subscription repo
-
-#Not tested, yet!
-read -p "Do you want to disable pve-enterprise repo and add pve-no-subscription repo (y/N)? " response
-
-if [ "${response,,}" == "y" ]; then
-    if [[ "$(uname -r)" == *"-pve" ]]; then
-        echo "Deactivating pve-enterprise repository"
-        mv /etc/apt/sources.list.d/pve-enterprise.list /etc/apt/sources.list.d/pve-enterprise.list.bak > /dev/null 2>&1
-        echo "Activating pve-no-subscription repository"
-        q=$(cat /etc/apt/sources.list | grep "pve-no-subscription")
-        if [ $? -gt 0 ]; then
-            echo "deb http://download.proxmox.com/debian/pve $VERSION_CODENAME pve-no-subscription" >> /etc/apt/sources.list
-        fi
-        rm -f /etc/apt/sources.list.d/pve-no-subscription.list
-    fi
-fi
-
-echo "Getting latest package lists"
-apt update > /dev/null 2>&1
-
-# include interfaces.d to enable SDN features
-q=$(cat /etc/network/interfaces | grep "source /etc/network/interfaces.d/*")
-if [ $? -gt 0 ]; then
-    echo "source /etc/network/interfaces.d/*" >> /etc/network/interfaces
-fi
-
-# update system and install basic tools
-echo "Upgrading system to latest version - Depending on your version this could take a while..."
-DEBIAN_FRONTEND=noninteractive DEBIAN_PRIORITY=critical apt -y -qq dist-upgrade > /dev/null 2>&1
-echo "Installing toolset - Depending on your version this could take a while..."
-DEBIAN_FRONTEND=noninteractive DEBIAN_PRIORITY=critical apt -y -qq install $TOOLS > /dev/null 2>&1
-
-# configure zfs-auto-snapshot
-for interval in "${!auto_snap_keep[@]}"; do
-    echo "Setting zfs-auto-snapshot retention: $interval = ${auto_snap_keep[$interval]}"
-    if [[ "$interval" == "frequent" ]]; then
-        CURRENT=$(cat /etc/cron.d/zfs-auto-snapshot | grep keep | cut -d' ' -f19 | cut -d '=' -f2)
-        if [[ "${auto_snap_keep[$interval]}" != "$CURRENT" ]]; then
-            rpl "keep=$CURRENT" "keep=${auto_snap_keep[$interval]}" /etc/cron.d/zfs-auto-snapshot > /dev/null 2>&1
-        fi
-    else
-        CURRENT=$(cat /etc/cron.$interval/zfs-auto-snapshot | grep keep | cut -d' ' -f6 | cut -d'=' -f2)
-        if [[ "${auto_snap_keep[$interval]}" != "$CURRENT" ]]; then
-            rpl "keep=$CURRENT" "keep=${auto_snap_keep[$interval]}" /etc/cron.$interval/zfs-auto-snapshot > /dev/null 2>&1
-        fi
-    fi
-done
-
-echo "Configuring swappiness"
-echo "vm.swappiness=$SWAPPINESS" > /etc/sysctl.d/swappiness.conf
-sysctl -w vm.swappiness=$SWAPPINESS
-
-echo "Configuring pve-conf-backup"
-# create backup jobs of /etc
-zfs list $PVE_CONF_BACKUP_TARGET > /dev/null 2>&1
-if [ $? -ne 0 ]; then
-    zfs create $PVE_CONF_BACKUP_TARGET
-fi
-
-if [[ "$(df -h -t zfs | grep /$ | cut -d ' ' -f1)" == "rpool/ROOT/pve-1" ]] ; then
-  echo "$PVE_CONF_BACKUP_CRON_TIMER root rsync -va --delete /etc /$PVE_CONF_BACKUP_TARGET > /$PVE_CONF_BACKUP_TARGET/pve-conf-backup.log" > /etc/cron.d/pve-conf-backup
-fi
-
-ZFS_ARC_MIN_BYTES=$((ZFS_ARC_MIN_MEGABYTES * 1024 *1024))
-ZFS_ARC_MAX_BYTES=$((ZFS_ARC_MAX_MEGABYTES * 1024 *1024))
-
-echo "Adjusting ZFS level 1 arc"
-echo $ZFS_ARC_MIN_BYTES > /sys/module/zfs/parameters/zfs_arc_min
-echo $ZFS_ARC_MAX_BYTES > /sys/module/zfs/parameters/zfs_arc_max
-
-cat << EOF > /etc/modprobe.d/zfs.conf
-options zfs zfs_arc_max=$ZFS_ARC_MAX_BYTES
-options zfs zfs_arc_min=$ZFS_ARC_MIN_BYTES
-EOF
-
-if [[ "$install_checkmk" == "y" ]]; then
-    echo "Installing checkmk agent..."
-    if [[ $( echo -n "$(openssl s_client -connect $(echo $cmk_agent_url | cut -d'/' -f3):443  <<< "Q" 2>/dev/null | grep "Verify return code" | cut -d ' ' -f4)" ) -gt 0 ]]; then
-        wget_opts="--no-check-certificate"
-        curl_opts="--insecure"
-    fi
-    wget -q -O /usr/local/bin/check_mk_agent $wget_opts $cmk_agent_url/check_mk/agents/check_mk_agent.linux
-    wget -q -O /usr/local/bin/mk-job $wget_opts $cmk_agent_url/check_mk/agents/mk-job
-    wget -q -O /usr/local/bin/check_mk_caching_agent  $wget_opts $cmk_agent_url/check_mk/agents/check_mk_caching_agent.linux
-    wget -q -O /usr/local/bin/waitmax  $wget_opts $cmk_agent_url/check_mk/agents/waitmax
-    chmod +x /usr/local/bin/check_mk_agent
-    chmod +x /usr/local/bin/mk-job
-    chmod +x /usr/local/bin/check_mk_caching_agent
-    chmod +x /usr/local/bin/waitmax
-    /usr/local/bin/check_mk_agent > /dev/null
-    wget -q -O /etc/systemd/system/check_mk.socket $wget_opts $cmk_agent_url/check_mk/agents/cfg_examples/systemd/check_mk.socket
-    cat << EOF > /etc/systemd/system/check_mk@.service
-# systemd service definition file
-[Unit]
-Description=Check_MK
-
-[Service]
-# "-" path prefix makes systemd record the exit code,
-# but the unit is not set to failed.
-ExecStart=-/usr/local/bin/check_mk_agent
-Type=forking
-
-User=root
-Group=root
-
-StandardInput=socket
-EOF
-
-    mkdir -p /etc/check_mk
-    if [[ "$cmk_encrypt" == "y" ]]; then
-        mkdir -p /etc/check_mk
-        cat << EOF > /etc/check_mk/encryption.cfg
-ENCRYPTED=yes
-PASSPHRASE='$cmk_enc_pass'
-EOF
-    chmod 600 /etc/check_mk/encryption.cfg
-    fi
-
-    mkdir -p /var/lib/check_mk_agent
-    mkdir -p /var/lib/check_mk_agent/spool
-    mkdir -p /var/lib/check_mk_agent/job
-    mkdir -p /usr/lib/check_mk_agent/local
-    mkdir -p /usr/lib/check_mk_agent/plugins
-    wget -q -O /usr/lib/check_mk_agent/plugins/smart $wget_opts $cmk_agent_url/check_mk/agents/plugins/smart
-    chmod +x /usr/lib/check_mk_agent/plugins/smart
-    wget -q -O /usr/lib/check_mk_agent/plugins/mk_inventory $wget_opts $cmk_agent_url/check_mk/agents/plugins/mk_inventory.linux
-    chmod +x /usr/lib/check_mk_agent/plugins/mk_inventory
-    wget -q -O /usr/lib/check_mk_agent/plugins/mk_apt $wget_opts $cmk_agent_url/check_mk/agents/plugins/mk_apt
-    chmod +x /usr/lib/check_mk_agent/plugins/mk_apt
-    #LocalDirectory: /usr/lib/check_mk_agent/local
-    systemctl daemon-reload
-    systemctl enable check_mk.socket
-    systemctl restart sockets.target
-
-    if [[ "$cmk_register" == "y" ]]; then
-        cmk_request="request={\"hostname\":\"$(echo -n $(hostname -f))\",\"folder\":\"$cmk_folder\",\"attributes\":{\"ipaddress\":\"$cmk_reg_ip\",\"site\":\"$cmk_site\",\"tag_agent\":\"cmk-agent\"},\"create_folders\":\"1\"}"
-        curl $curl_opts "$cmk_agent_url/check_mk/webapi.py?action=add_host&_secret=$cmk_secret&_username=automation" -d $cmk_request
-        curl $curl_opts "$cmk_agent_url/check_mk/webapi.py?action=activate_changes&_secret=$cmk_secret&_username=automation" -d "request={\"sites\":[\"$cmk_site\"],\"allow_foreign_changes\":\"0\"}"
-    fi
-fi
-
-echo "Updating initramfs - This will take some time..."
-update-initramfs -u -k all > /dev/null 2>&1
-
-echo "Proxmox postinstallation finished!"