diff --git a/util/normalize.lua b/util/normalize.lua
index 52eeab8..8d09399 100644
--- a/util/normalize.lua
+++ b/util/normalize.lua
@@ -7,7 +7,7 @@ and add individual player names to recipient list
 function mail.normalize_players_and_add_recipients(field, recipients, undeliverable)
     local order = mail.parse_player_list(field)
     for _, recipient_name in ipairs(order) do
-        if mail.split(recipient_name, "@")[1] == "" then -- in case of maillist
+        if recipient_name:split("@")[1] == "" then -- in case of maillist
             recipients[recipient_name] = true
         else -- in case of playerˇ
             if not minetest.player_exists(recipient_name) then