Double quotes

src/freedombone

     echo '        if [ -f /etc/nginx/sites-available/$LETSENCRYPT_DOMAIN ]; then' >> $renewals_script
     echo '            ${PROJECT_NAME}-renew-cert -h $LETSENCRYPT_DOMAIN -p letsencrypt' >> $renewals_script
     echo '            if [ ! "$?" = "0" ]; then' >> $renewals_script
-    echo -n "                echo '$renewal_failure_msg' | mail -s '$renewal_email_title' " >> $renewals_script
+    echo -n "                echo \"$renewal_failure_msg\" | mail -s \"$renewal_email_title\" " >> $renewals_script
     echo '$ADMIN_EMAIL_ADDRESS' >> $renewals_script
     echo '            fi' >> $renewals_script
     echo '        fi' >> $renewals_script