diff --git a/auto_config.sh b/auto_config.sh
index 69d2719..342d2ae 100755
--- a/auto_config.sh
+++ b/auto_config.sh
@@ -110,11 +110,24 @@ apt-get -y install      \
     apt-listchanges     \
     logrotate
 
+################################################################################
+
 # Configure auto updates
-sed -i \
-    -e "s#^//Unattended-Upgrade::Mail .*#Unattended-Upgrade::Mail '$UNATTENDED_EMAIL';#" \
-    -e 's#^//Unattended-Upgrade::MailOnlyOnError .*#Unattended-Upgrade::MailOnlyOnError "true";#' \
-     /etc/apt/apt.conf.d/50unattended-upgrades
+UNA_FILE="/etc/apt/apt.conf.d/50unattended-upgrades"
+# email setting
+if ! grep -q '^Unattended-Upgrade::Mail ' $UNA_FILE ; then
+    echo "Unattended-Upgrade::Mail '$UNATTENDED_EMAIL';" >> $UNA_FILE
+else
+    sed -i "s/Unattended-Upgrade::Mail .*/Unattended-Upgrade::Mail '$UNATTENDED_EMAIL';/" $UNA_FILE
+fi
+# MailOnlyOnError
+if ! grep -q '^Unattended-Upgrade::MailOnlyOnError ' $UNA_FILE ; then
+    echo "Unattended-Upgrade::MailOnlyOnError 'true';" >> $UNA_FILE
+else
+    sed -i "s/Unattended-Upgrade::MailOnlyOnError .*/Unattended-Upgrade::MailOnlyOnError 'true';/" $UNA_FILE
+fi
+
+################################################################################
 
 # Set git global config
 git config --global user.name "$GIT_USERNAME"