More checking for email creation

src/freedombone-base-email

     read_config_param MY_EMAIL_ADDRESS
     read_config_param DH_KEYLENGTH
 
-    if [ ${#MY_EMAIL_ADDRESS} -lt 3 ]; then
+    if [ ! $MY_USERNAME ]; then
+        echo $'No username for email installation'
+        exit 73672
+    fi
+    if [ ! $DEFAULT_DOMAIN_NAME ]; then
+        echo $'No default domain name for email installation'
+        exit 57634
+    fi
+
+    my_email="$MY_EMAIL_ADDRESS"
+    if [ ${#my_email} -lt 3 ]; then
         MY_EMAIL_ADDRESS=${MY_USERNAME}@${DEFAULT_DOMAIN_NAME}
+        write_config_param "MY_EMAIL_ADDRESS" "$MY_EMAIL_ADDRESS"
     fi
 
     install_email_basic