diff --git a/api.lua b/api.lua
index 4fde5c7..159efea 100644
--- a/api.lua
+++ b/api.lua
@@ -69,7 +69,7 @@ function mail.send(m)
 		extra_log = ""
 	end
 
-	minetest.log("action", f("[mail] %q send mail to %q%s with subject %q and body %q",
+	core.log("action", f("[mail] %q send mail to %q%s with subject %q and body %q",
 		m.from, m.to, extra_log, m.subject, m.body
 	))
 
@@ -122,7 +122,7 @@ function mail.save_draft(m)
 	-- defaults
 	m.subject = m.subject or "(No subject)"
 
-	minetest.log("verbose", f("[mail] %q saves draft with subject %q and body %q",
+	core.log("verbose", f("[mail] %q saves draft with subject %q and body %q",
 		m.from, m.subject, m.body
 	))
 
diff --git a/chatcommands.lua b/chatcommands.lua
index a152274..544350f 100644
--- a/chatcommands.lua
+++ b/chatcommands.lua
@@ -1,4 +1,4 @@
-minetest.register_chatcommand("mail",{
+core.register_chatcommand("mail",{
 	description = "Open the mail interface",
 	func = function(name, param)
 		if #param > 0 then -- if param is not empty
diff --git a/gui.lua b/gui.lua
index 1a4d0a6..fe399e5 100644
--- a/gui.lua
+++ b/gui.lua
@@ -1,5 +1,5 @@
 
-if minetest.get_modpath("unified_inventory") then
+if core.get_modpath("unified_inventory") then
 
 	unified_inventory.register_button("mail", {
 			type = "image",
@@ -11,7 +11,7 @@ if minetest.get_modpath("unified_inventory") then
 		})
 end
 
-if minetest.get_modpath("sfinv_buttons") then
+if core.get_modpath("sfinv_buttons") then
 	sfinv_buttons.register_button("mail", {
 			title = "Mail",
 			image = "mail_button.png",
diff --git a/hud.lua b/hud.lua
index 7eca2a2..6680447 100644
--- a/hud.lua
+++ b/hud.lua
@@ -1,7 +1,7 @@
 
 local huddata = {}
 
-minetest.register_on_joinplayer(function(player)
+core.register_on_joinplayer(function(player)
 	local name = player:get_player_name()
 	local data = {}
 
@@ -27,7 +27,7 @@ minetest.register_on_joinplayer(function(player)
 	huddata[name] = data
 end)
 
-minetest.register_on_leaveplayer(function(player)
+core.register_on_leaveplayer(function(player)
 	local name = player:get_player_name()
 	huddata[name] = nil
 end)
@@ -35,7 +35,7 @@ end)
 
 function mail.hud_update(playername, messages)
 	local data = huddata[playername]
-	local player = minetest.get_player_by_name(playername)
+	local player = core.get_player_by_name(playername)
 
 	if not data or not player then
 		return
diff --git a/init.lua b/init.lua
index 8de0bec..2643f42 100644
--- a/init.lua
+++ b/init.lua
@@ -3,10 +3,10 @@ mail = {
 	version = 3,
 
 	-- mod storage
-	storage = minetest.get_mod_storage(),
+	storage = core.get_mod_storage(),
 
 	-- translation
-	S = minetest.get_translator(minetest.get_current_modname()),
+	S = core.get_translator(core.get_current_modname()),
 
 	-- ui theme prepend
 	theme = "",
@@ -39,12 +39,12 @@ mail = {
 	message_drafts = {}
 }
 
-if minetest.get_modpath("default") then
+if core.get_modpath("default") then
 	mail.theme = default.gui_bg .. default.gui_bg_img
 end
 
 -- sub files
-local MP = minetest.get_modpath(minetest.get_current_modname())
+local MP = core.get_modpath(core.get_current_modname())
 dofile(MP .. "/util/init.lua")
 dofile(MP .. "/chatcommands.lua")
 dofile(MP .. "/migrate.lua")
@@ -60,7 +60,7 @@ dofile(MP .. "/ui/init.lua")
 -- migrate storage
 mail.migrate()
 
-if minetest.get_modpath("mtt") then
+if core.get_modpath("mtt") then
 	dofile(MP .. "/mtt.lua")
 	dofile(MP .. "/api.spec.lua")
 	dofile(MP .. "/migrate.spec.lua")
diff --git a/migrate.lua b/migrate.lua
index 4084397..e4f72e6 100644
--- a/migrate.lua
+++ b/migrate.lua
@@ -2,12 +2,12 @@ local STORAGE_VERSION_KEY = "@@version"
 local CURRENT_VERSION = 3.1
 
 local function migrate_v1_to_v3()
-	local file = io.open(minetest.get_worldpath().."/mail.db", "r")
+	local file = io.open(core.get_worldpath().."/mail.db", "r")
 	assert(file)
 	print("[mail] Migration from v1 to v3 database")
 
 	local data = file:read("*a")
-	local oldmails = minetest.deserialize(data)
+	local oldmails = core.deserialize(data)
 	file:close()
 
 	for name, oldmessages in pairs(oldmails) do
@@ -28,7 +28,7 @@ local function migrate_v1_to_v3()
 
 	-- rename file
 	print("[mail,v1] migration done, renaming old mail.db")
-	os.rename(minetest.get_worldpath().."/mail.db", minetest.get_worldpath().."/mail.db.old")
+	os.rename(core.get_worldpath().."/mail.db", core.get_worldpath().."/mail.db.old")
 end
 
 local function read_json_file(path)
@@ -36,7 +36,7 @@ local function read_json_file(path)
 	local content = {}
 	if file then
 		local json = file:read("*a")
-		content = minetest.parse_json(json or "[]") or {}
+		content = core.parse_json(json or "[]") or {}
 		file:close()
 	end
 	return content
@@ -44,13 +44,13 @@ end
 
 -- migrate from v2 to v3 database
 local function migrate_v2_to_v3()
-	local maildir = minetest.get_worldpath().."/mails"
-	minetest.mkdir(maildir) -- if necessary (eg. first login)
+	local maildir = core.get_worldpath().."/mails"
+	core.mkdir(maildir) -- if necessary (eg. first login)
 	print("[mail] Migration from v2 to v3 database")
 
 	-- defer execution until auth-handler ready (first server-step)
-	minetest.after(0, function()
-		for playername, _ in minetest.get_auth_handler().iterate() do
+	core.after(0, function()
+		for playername, _ in core.get_auth_handler().iterate() do
 			local entry = mail.get_storage_entry(playername)
 
 			local player_contacts = read_json_file(maildir .. "/contacts/" .. playername .. ".json")
@@ -110,7 +110,7 @@ local function is_uuid_existing(uuid)
 			end
 		end
 	else
-		for p, _ in minetest.get_auth_handler().iterate() do
+		for p, _ in core.get_auth_handler().iterate() do
 			local result = search_boxes(p, boxes, uuid)
 			if result then return result end
 		end
@@ -168,7 +168,7 @@ local function fix_box_duplicate_uuids(playername, box)
 					end
 				end
 			else
-				for p, _ in minetest.get_auth_handler().iterate() do
+				for p, _ in core.get_auth_handler().iterate() do
 					replace_other_player_message_uuid(p, m, uuid, new_uuid)
 				end
 			end
@@ -195,8 +195,8 @@ local function repair_storage()
 			end
 		end
 	else
-		minetest.after(0, function()
-			for p, _ in minetest.get_auth_handler().iterate() do
+		core.after(0, function()
+			for p, _ in core.get_auth_handler().iterate() do
 				fix_player_duplicate_uuids(p)
 			end
 		end)
@@ -213,7 +213,7 @@ function mail.migrate()
 	end
 
 	-- check for v1 storage
-	local v1_file = io.open(minetest.get_worldpath().."/mail.db", "r")
+	local v1_file = io.open(core.get_worldpath().."/mail.db", "r")
 	if v1_file then
 		-- v1 to v3
 		migrate_v1_to_v3()
diff --git a/mtt.lua b/mtt.lua
index 7c8cf0b..ba6054e 100644
--- a/mtt.lua
+++ b/mtt.lua
@@ -1,7 +1,7 @@
 
 mtt.register("setup", function(callback)
     -- create test players
-    local auth_handler = minetest.get_auth_handler()
+    local auth_handler = core.get_auth_handler()
     auth_handler.set_password("player1", "")
     auth_handler.set_password("player2", "")
     auth_handler.set_password("player3", "")
diff --git a/onjoin.lua b/onjoin.lua
index ef602e5..56ec965 100644
--- a/onjoin.lua
+++ b/onjoin.lua
@@ -1,8 +1,8 @@
 -- translation
 local S = mail.S
 
-minetest.register_on_joinplayer(function(player)
-	minetest.after(2, function(name)
+core.register_on_joinplayer(function(player)
+	core.after(2, function(name)
 		local entry = mail.get_storage_entry(name)
 		local messages = entry.inbox
 		mail.hud_update(name, messages)
@@ -16,8 +16,8 @@ minetest.register_on_joinplayer(function(player)
 		end
 
 		if unreadcount > 0 and mail.get_setting(name, "onjoin_notifications") then
-			minetest.chat_send_player(name,
-				minetest.colorize(mail.get_color("new"), "(" .. unreadcount .. ") " .. S("You have mail! Type /mail to read")))
+			core.chat_send_player(name,
+				core.colorize(mail.get_color("new"), "(" .. unreadcount .. ") " .. S("You have mail! Type /mail to read")))
 		end
 	end, player:get_player_name())
 end)
diff --git a/player_recipients.lua b/player_recipients.lua
index 0812dfb..2511a96 100644
--- a/player_recipients.lua
+++ b/player_recipients.lua
@@ -1,7 +1,7 @@
 -- translation
 local S = mail.S
 
-local has_canonical_name = minetest.get_modpath("canonical_name")
+local has_canonical_name = core.get_modpath("canonical_name")
 
 mail.register_on_player_receive(function(name, msg)
 	-- add to inbox
@@ -13,16 +13,16 @@ mail.register_on_player_receive(function(name, msg)
 	local mail_alert = S("You have a new message from @1! Subject: @2",  msg.from, msg.subject) ..
 	"\n" .. S("To view it, type /mail")
 	local inventory_alert = S("You could also use the button in your inventory.")
-	local player = minetest.get_player_by_name(name)
+	local player = core.get_player_by_name(name)
 	if player then
 		if mail.get_setting(name, "chat_notifications") == true then
-			minetest.chat_send_player(name, mail_alert)
-			if minetest.get_modpath("unified_inventory") or minetest.get_modpath("sfinv_buttons") then
-				minetest.chat_send_player(name, inventory_alert)
+			core.chat_send_player(name, mail_alert)
+			if core.get_modpath("unified_inventory") or core.get_modpath("sfinv_buttons") then
+				core.chat_send_player(name, inventory_alert)
 			end
 		end
 		if mail.get_setting(name, "sound_notifications") == true then
-			minetest.sound_play("mail_notif", {to_player=name})
+			core.sound_play("mail_notif", {to_player=name})
 		end
 		local receiver_entry = mail.get_storage_entry(name)
 		local receiver_messages = receiver_entry.inbox
@@ -31,7 +31,7 @@ mail.register_on_player_receive(function(name, msg)
 end)
 
 mail.register_recipient_handler(function(_, pname)
-	if not minetest.player_exists(pname) then
+	if not core.player_exists(pname) then
 		return nil
 	end
 	return true, function(msg)
diff --git a/storage.lua b/storage.lua
index 901b985..77974df 100644
--- a/storage.lua
+++ b/storage.lua
@@ -31,7 +31,7 @@ function mail.get_storage_entry(playername)
 		entry = populate_entry()
 	else
 		-- deserialize existing entry
-		local e = minetest.parse_json(str)
+		local e = core.parse_json(str)
 		entry = populate_entry(e)
 	end
 
@@ -55,7 +55,7 @@ end
 local function save_worker()
 	for key, entry in pairs(save_queued_entries) do
 		-- write to backend
-		mail.storage:set_string(key, minetest.write_json(entry))
+		mail.storage:set_string(key, core.write_json(entry))
 	end
 
 	-- clear queue
@@ -65,13 +65,13 @@ local function save_worker()
 	cache = {}
 
 	-- save every second
-	minetest.after(1, save_worker)
+	core.after(1, save_worker)
 end
 
 -- start save-worker loop
 save_worker()
 -- save on shutdown
-minetest.register_on_shutdown(save_worker)
+core.register_on_shutdown(save_worker)
 
 -- get a mail by id from the players in- or outbox
 function mail.get_message(playername, msg_id)
@@ -392,20 +392,20 @@ local function extract_maillists_main(receivers, maillists_owner, expanded_recei
 	for _, receiver in pairs(receivers) do
 		if seen[receiver] then
 			-- Do not add/expand this receiver as it is already seen
-			minetest.log("verbose", ("mail: ignoring duplicate receiver %q during maillist expansion"):format(receiver))
+			core.log("verbose", ("mail: ignoring duplicate receiver %q during maillist expansion"):format(receiver))
 		elseif string.find(receiver, "^@") then
 			seen[receiver] = true
 			local listname = string.sub(receiver, 2)
 			local maillist = mail.get_maillist_by_name(maillists_owner, listname)
 			if maillist then
-				minetest.log("verbose", ("mail: expanding maillist %q"):format(listname))
+				core.log("verbose", ("mail: expanding maillist %q"):format(listname))
 				for _, entry in ipairs(maillist.players) do
 					extract_maillists_main(entry, maillists_owner, expanded_receivers, seen)
 				end
 			end
 		else
 			seen[receiver] = true
-			minetest.log("verbose", ("mail: adding %q to receiver list during maillist expansion"):format(receiver))
+			core.log("verbose", ("mail: adding %q to receiver list during maillist expansion"):format(receiver))
 			table.insert(expanded_receivers, receiver)
 		end
 	end
diff --git a/ui/about.lua b/ui/about.lua
index cd50405..b8db215 100644
--- a/ui/about.lua
+++ b/ui/about.lua
@@ -119,10 +119,10 @@ function mail.show_about(name)
 
 	formspec = formspec .. mail.theme
 
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -141,10 +141,10 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
         mail.show_about(playername)
 
 	elseif fields.github then
-		minetest.chat_send_player(playername, "https://github.com/mt-mods/mail")
+		core.chat_send_player(playername, "https://github.com/mt-mods/mail")
 
 	elseif fields.contentdb then
-		minetest.chat_send_player(playername, "https://content.minetest.net/packages/mt-mods/mail")
+		core.chat_send_player(playername, "https://content.minetest.net/packages/mt-mods/mail")
 	elseif fields.contributor_grouping then
 		mail.selected_idxs.contributor_grouping[playername] = fields.contributor_grouping
 		mail.show_about(playername)
diff --git a/ui/compose.lua b/ui/compose.lua
index 62d16a2..71750f3 100644
--- a/ui/compose.lua
+++ b/ui/compose.lua
@@ -20,18 +20,18 @@ function mail.show_compose(name, to, subject, body, cc, bcc, id)
 		]] .. mail.theme
 
 	formspec = string.format(formspec,
-		minetest.formspec_escape(to) or "",
-		minetest.formspec_escape(cc) or "",
-		minetest.formspec_escape(bcc) or "",
-		minetest.formspec_escape(subject) or "",
-		minetest.formspec_escape(body) or "")
+		core.formspec_escape(to) or "",
+		core.formspec_escape(cc) or "",
+		core.formspec_escape(bcc) or "",
+		core.formspec_escape(subject) or "",
+		core.formspec_escape(body) or "")
 
 	mail.selected_idxs.message[name] = id or mail.new_uuid()
 
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -63,7 +63,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
             body = fields.body,
         })
         if not success then
-            minetest.chat_send_player(name, err)
+            core.chat_send_player(name, err)
             return
         end
 
@@ -87,7 +87,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
             end
         end
 
-        minetest.after(0.5, function()
+        core.after(0.5, function()
             mail.selected_idxs.drafts[name] = nil
             mail.show_mail_menu(name)
         end)
diff --git a/ui/contacts.lua b/ui/contacts.lua
index 3978251..7c09d65 100644
--- a/ui/contacts.lua
+++ b/ui/contacts.lua
@@ -14,10 +14,10 @@ local contacts_formspec = "size[8,9;]" .. mail.theme .. [[
 
 function mail.show_contacts(name)
     local formspec = contacts_formspec .. mail.compile_contact_list(name, mail.selected_idxs.contacts[name])
-    minetest.show_formspec(name, FORMNAME, formspec)
+    core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -26,7 +26,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	local contacts = mail.get_contacts(name)
 
 	if fields.contacts then
-		local evt = minetest.explode_table_event(fields.contacts)
+		local evt = core.explode_table_event(fields.contacts)
 		for k, _, i in mail.pairs_by_keys(contacts) do
 			if i == evt.row - 1 then
 				mail.selected_idxs.contacts[name] = tonumber(k)
diff --git a/ui/drafts.lua b/ui/drafts.lua
index 003e3cc..3a98b6b 100644
--- a/ui/drafts.lua
+++ b/ui/drafts.lua
@@ -32,14 +32,14 @@ function mail.show_drafts(name)
 		for _, message in ipairs(messages) do
 			formspec[#formspec + 1] = ","
 			formspec[#formspec + 1] = ","
-			formspec[#formspec + 1] = minetest.formspec_escape(message.to)
+			formspec[#formspec + 1] = core.formspec_escape(message.to)
 			formspec[#formspec + 1] = ","
 			if message.subject ~= "" then
 				if string.len(message.subject) > 30 then
-					formspec[#formspec + 1] = minetest.formspec_escape(string.sub(message.subject, 1, 27))
+					formspec[#formspec + 1] = core.formspec_escape(string.sub(message.subject, 1, 27))
 					formspec[#formspec + 1] = "..."
 				else
-					formspec[#formspec + 1] = minetest.formspec_escape(message.subject)
+					formspec[#formspec + 1] = core.formspec_escape(message.subject)
 				end
 			else
 				formspec[#formspec + 1] = S("(No subject)")
@@ -53,5 +53,5 @@ function mail.show_drafts(name)
 	else
 		formspec[#formspec + 1] = "]label[2.25,4.5;" .. S("No drafts") .. "]"
 	end
-    minetest.show_formspec(name, "mail:drafts", table.concat(formspec, ""))
+    core.show_formspec(name, "mail:drafts", table.concat(formspec, ""))
 end
diff --git a/ui/edit_contact.lua b/ui/edit_contact.lua
index c8e00e3..e7885df 100644
--- a/ui/edit_contact.lua
+++ b/ui/edit_contact.lua
@@ -24,12 +24,12 @@ function mail.show_edit_contact(name, contact_name, note, illegal_name_hint)
 	end
 	formspec = formspec .. mail.theme
 	formspec = string.format(formspec,
-		minetest.formspec_escape(contact_name or ""),
-		minetest.formspec_escape(note or ""))
-	minetest.show_formspec(name, FORMNAME, formspec)
+		core.formspec_escape(contact_name or ""),
+		core.formspec_escape(note or ""))
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
diff --git a/ui/edit_maillists.lua b/ui/edit_maillists.lua
index ac36022..4e3d595 100644
--- a/ui/edit_maillists.lua
+++ b/ui/edit_maillists.lua
@@ -25,13 +25,13 @@ function mail.show_edit_maillist(playername, maillist_name, desc, players, illeg
 	end
 	formspec = formspec .. mail.theme
 	formspec = string.format(formspec,
-		minetest.formspec_escape(maillist_name or ""),
-		minetest.formspec_escape(desc or ""),
-		minetest.formspec_escape(players or ""))
-	minetest.show_formspec(playername, FORMNAME, formspec)
+		core.formspec_escape(maillist_name or ""),
+		core.formspec_escape(desc or ""),
+		core.formspec_escape(players or ""))
+	core.show_formspec(playername, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
diff --git a/ui/events.lua b/ui/events.lua
index 2686c9d..34c9533 100644
--- a/ui/events.lua
+++ b/ui/events.lua
@@ -14,7 +14,7 @@ local function nonempty(x)
  return ((type(x)=="table")and(#x>0))
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
     if formname ~= "mail:inbox" and formname ~= "mail:outbox"
     and formname ~= "mail:drafts" and formname ~= "mail:trash" then
         return
@@ -59,7 +59,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 
     -- Hanmdle formspec event
     if fields.inbox then -- inbox table
-        local evt = minetest.explode_table_event(fields.inbox)
+        local evt = core.explode_table_event(fields.inbox)
         if evt.row == 1 then -- header
             if mail.selected_idxs.sortfield[name] == evt.column-1 then -- if already this field, then change direction
                 mail.selected_idxs.sortdirection[name] = mail.selected_idxs.sortdirection[name] == "2" and "1" or "2"
@@ -105,7 +105,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
     end
 
     if fields.outbox then -- outbox table
-        local evt = minetest.explode_table_event(fields.outbox)
+        local evt = core.explode_table_event(fields.outbox)
         if evt.row == 1 then -- header
             if mail.selected_idxs.sortfield[name] == evt.column-1 then -- if already this field, then change direction
                 mail.selected_idxs.sortdirection[name] = mail.selected_idxs.sortdirection[name] == "2" and "1" or "2"
@@ -151,7 +151,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
     end
 
     if fields.drafts then -- drafts table
-        local evt = minetest.explode_table_event(fields.drafts)
+        local evt = core.explode_table_event(fields.drafts)
         if evt.row == 1 then -- header
             if mail.selected_idxs.sortfield[name] == evt.column-1 then -- if already this field, then change direction
                 mail.selected_idxs.sortdirection[name] = mail.selected_idxs.sortdirection[name] == "2" and "1" or "2"
@@ -176,7 +176,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
     end
 
     if fields.trash then -- trash table
-        local evt = minetest.explode_table_event(fields.trash)
+        local evt = core.explode_table_event(fields.trash)
         if evt.row == 1 then -- header
             if mail.selected_idxs.sortfield[name] == evt.column-1 then -- if already this field, then change direction
                 mail.selected_idxs.sortdirection[name] = mail.selected_idxs.sortdirection[name] == "2" and "1" or "2"
diff --git a/ui/inbox.lua b/ui/inbox.lua
index 526fc6f..0553931 100644
--- a/ui/inbox.lua
+++ b/ui/inbox.lua
@@ -109,14 +109,14 @@ function mail.show_inbox(name, sortfieldindex, sortdirection, filter)
             end
             formspec[#formspec + 1] = "," .. mail.get_color(displayed_color)
             formspec[#formspec + 1] = ","
-            formspec[#formspec + 1] = minetest.formspec_escape(message.from)
+            formspec[#formspec + 1] = core.formspec_escape(message.from)
             formspec[#formspec + 1] = ","
             if message.subject ~= "" then
                 if string.len(message.subject) > 30 then
-                    formspec[#formspec + 1] = minetest.formspec_escape(string.sub(message.subject, 1, 27))
+                    formspec[#formspec + 1] = core.formspec_escape(string.sub(message.subject, 1, 27))
                     formspec[#formspec + 1] = "..."
                 else
-                    formspec[#formspec + 1] = minetest.formspec_escape(message.subject)
+                    formspec[#formspec + 1] = core.formspec_escape(message.subject)
                 end
             else
                 formspec[#formspec + 1] = S("(No subject)")
@@ -127,5 +127,5 @@ function mail.show_inbox(name, sortfieldindex, sortdirection, filter)
         formspec[#formspec + 1] = "]label[2.25,4.5;" .. S("No mail") .. "]"
     end
 
-    minetest.show_formspec(name, "mail:inbox", table.concat(formspec, ""))
+    core.show_formspec(name, "mail:inbox", table.concat(formspec, ""))
 end
diff --git a/ui/init.lua b/ui/init.lua
index 5e6443c..b568620 100644
--- a/ui/init.lua
+++ b/ui/init.lua
@@ -1,5 +1,5 @@
 -- sub files
-local MP = minetest.get_modpath(minetest.get_current_modname())
+local MP = core.get_modpath(core.get_current_modname())
 
 dofile(MP .. "/ui/inbox.lua")
 dofile(MP .. "/ui/outbox.lua")
diff --git a/ui/maillists.lua b/ui/maillists.lua
index 9ba8a52..2d73a78 100644
--- a/ui/maillists.lua
+++ b/ui/maillists.lua
@@ -19,14 +19,14 @@ function mail.show_maillists(name)
 		for _, maillist in ipairs(maillists) do
 			formspec[#formspec + 1] = ","
 			formspec[#formspec + 1] = ","
-			formspec[#formspec + 1] = "@" .. minetest.formspec_escape(maillist.name)
+			formspec[#formspec + 1] = "@" .. core.formspec_escape(maillist.name)
 			formspec[#formspec + 1] = ","
 			if maillist.desc ~= "" then
 				if string.len(maillist.desc or "") > 30 then
-					formspec[#formspec + 1] = minetest.formspec_escape(string.sub(maillist.desc, 1, 27))
+					formspec[#formspec + 1] = core.formspec_escape(string.sub(maillist.desc, 1, 27))
 					formspec[#formspec + 1] = "..."
 				else
-					formspec[#formspec + 1] = minetest.formspec_escape(maillist.desc)
+					formspec[#formspec + 1] = core.formspec_escape(maillist.desc)
 				end
 			else
 				formspec[#formspec + 1] = S("(No description)")
@@ -40,10 +40,10 @@ function mail.show_maillists(name)
 	else
 		formspec[#formspec + 1] = "]label[2.25,4.5;" .. S("No maillist") .. "]"
 	end
-	minetest.show_formspec(name, FORMNAME, table.concat(formspec, ""))
+	core.show_formspec(name, FORMNAME, table.concat(formspec, ""))
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -52,7 +52,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	local maillists = mail.get_maillists(name)
 
 	if fields.maillists then
-		local evt = minetest.explode_table_event(fields.maillists)
+		local evt = core.explode_table_event(fields.maillists)
 		mail.selected_idxs.maillists[name] = evt.row - 1
 		if evt.type == "DCL" and maillists[mail.selected_idxs.maillists[name]] then
 			local maillist = mail.get_maillist_by_name(name, maillists[mail.selected_idxs.maillists[name]].name)
diff --git a/ui/message.lua b/ui/message.lua
index 7f3447e..dae4442 100644
--- a/ui/message.lua
+++ b/ui/message.lua
@@ -52,16 +52,16 @@ function mail.show_message(name, id)
 			tooltip[forward;]] .. S("Transfer message to other people") .. [[]
 		]] .. mail.theme
 
-	local from = minetest.formspec_escape(message.from) or ""
-	local to = minetest.formspec_escape(message.to) or ""
+	local from = core.formspec_escape(message.from) or ""
+	local to = core.formspec_escape(message.to) or ""
 	if string.len(to) > 70 then to = string.sub(to, 1, 67) .. "..." end
-	local cc = minetest.formspec_escape(message.cc) or ""
+	local cc = core.formspec_escape(message.cc) or ""
 	if string.len(cc) > 50 then cc = string.sub(cc, 1, 47) .. "..." end
 	local date = type(message.time) == "number"
-		and minetest.formspec_escape(os.date(mail.get_setting(name, "date_format"),
+		and core.formspec_escape(os.date(mail.get_setting(name, "date_format"),
 		message.time+3600*mail.get_setting(name, "timezone_offset"))) or ""
-	local subject = minetest.formspec_escape(message.subject) or ""
-	local body = minetest.formspec_escape(message.body) or ""
+	local subject = core.formspec_escape(message.subject) or ""
+	local body = core.formspec_escape(message.body) or ""
 	formspec = string.format(formspec, from, to, cc, date, subject, body)
 
 	if not message.read and mail.get_setting(name, "auto_marking_read") then
@@ -69,14 +69,14 @@ function mail.show_message(name, id)
 		mail.mark_read(name, id)
 	end
 
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
 function mail.reply(name, message)
 	if not message then
 		-- TODO: workaround for https://github.com/mt-mods/mail/issues/84
-		minetest.log("error", "[mail] reply called with nil message for player: " .. name)
-		minetest.log("error", "[mail] current mail-context: " .. dump(mail.selected_idxs))
+		core.log("error", "[mail] reply called with nil message for player: " .. name)
+		core.log("error", "[mail] current mail-context: " .. dump(mail.selected_idxs))
 		return
 	end
 	mail.show_compose(name, message.from, "Re: "..message.subject, interleave_msg(message.body))
@@ -85,8 +85,8 @@ end
 function mail.replyall(name, message)
 	if not message then
 		-- TODO: workaround for https://github.com/mt-mods/mail/issues/84
-		minetest.log("error", "[mail] replyall called with nil message for player: " .. name)
-		minetest.log("error", "[mail] current mail-context: " .. dump(mail.selected_idxs))
+		core.log("error", "[mail] replyall called with nil message for player: " .. name)
+		core.log("error", "[mail] current mail-context: " .. dump(mail.selected_idxs))
 		return
 	end
 
@@ -121,7 +121,7 @@ function mail.forward(name, message)
 	mail.show_compose(name, "", "Fw: " .. (message.subject or ""), interleave_msg(message.body))
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
diff --git a/ui/outbox.lua b/ui/outbox.lua
index 667bf1c..0a2a146 100644
--- a/ui/outbox.lua
+++ b/ui/outbox.lua
@@ -90,18 +90,18 @@ function mail.show_outbox(name, sortfieldindex, sortdirection, filter)
             formspec[#formspec + 1] = "," .. mail.get_color(displayed_color)
             formspec[#formspec + 1] = ","
 			if string.len(message.to) > 20 then
-				formspec[#formspec + 1] = minetest.formspec_escape(string.sub(message.to, 1, 17))
+				formspec[#formspec + 1] = core.formspec_escape(string.sub(message.to, 1, 17))
 				formspec[#formspec + 1] = "..."
 			else
-				formspec[#formspec + 1] = minetest.formspec_escape(message.to)
+				formspec[#formspec + 1] = core.formspec_escape(message.to)
 			end
             formspec[#formspec + 1] = ","
             if message.subject ~= "" then
                 if string.len(message.subject) > 30 then
-                    formspec[#formspec + 1] = minetest.formspec_escape(string.sub(message.subject, 1, 27))
+                    formspec[#formspec + 1] = core.formspec_escape(string.sub(message.subject, 1, 27))
                     formspec[#formspec + 1] = "..."
                 else
-                    formspec[#formspec + 1] = minetest.formspec_escape(message.subject)
+                    formspec[#formspec + 1] = core.formspec_escape(message.subject)
                 end
             else
                 formspec[#formspec + 1] = S("(No subject)")
@@ -112,5 +112,5 @@ function mail.show_outbox(name, sortfieldindex, sortdirection, filter)
         formspec[#formspec + 1] = "]label[2.25,4.5;" .. S("No mail") .. "]"
     end
 
-	minetest.show_formspec(name, "mail:outbox", table.concat(formspec, ""))
+	core.show_formspec(name, "mail:outbox", table.concat(formspec, ""))
 end
diff --git a/ui/receivers.lua b/ui/receivers.lua
index 64d775d..303c47b 100644
--- a/ui/receivers.lua
+++ b/ui/receivers.lua
@@ -1,5 +1,5 @@
 -- translation
-local S = minetest.get_translator("mail")
+local S = core.get_translator("mail")
 
 local FORMNAME = "mail:receivers"
 
@@ -23,7 +23,7 @@ function mail.show_receivers(name, id)
 			table[4,1.5;3.8,4.5;cc;%s]
 		]] .. mail.theme
 
-	local from = minetest.formspec_escape(message.from) or ""
+	local from = core.formspec_escape(message.from) or ""
 	local to = mail.parse_player_list(message.to or "")
 	local to_str = mail.get_color("header") .. "," .. S("To") .. ",,"
 	to_str = to_str .. table.concat(to, ",,")
@@ -31,13 +31,13 @@ function mail.show_receivers(name, id)
 	local cc_str = mail.get_color("header") .. "," .. S("CC") .. ",,"
 	cc_str = cc_str .. table.concat(cc, ",,")
 	local date = type(message.time) == "number"
-		and minetest.formspec_escape(os.date(mail.get_setting(name, "date_format"), message.time)) or ""
+		and core.formspec_escape(os.date(mail.get_setting(name, "date_format"), message.time)) or ""
 	formspec = string.format(formspec, from, date, to_str, cc_str)
 
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
diff --git a/ui/select_contact.lua b/ui/select_contact.lua
index 33438d1..c7eefda 100644
--- a/ui/select_contact.lua
+++ b/ui/select_contact.lua
@@ -39,10 +39,10 @@ function mail.show_select_contact(name, to, cc)
 		bcc = ""
 	end]]--
 	formspec = string.format(formspec, contacts, to, cc)--, bcc()
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -60,7 +60,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 		bcc = "bccremove"
 	}) do
 		if fields[k] then
-			local evt = minetest.explode_table_event(fields[k])
+			local evt = core.explode_table_event(fields[k])
 			mail.selected_idxs[k][name] = evt.row - 1
 			if evt.type == "DCL" and mail.selected_idxs[k][name] then
 				fields[action] = true
diff --git a/ui/settings.lua b/ui/settings.lua
index 9323fe5..a7b2c64 100644
--- a/ui/settings.lua
+++ b/ui/settings.lua
@@ -184,10 +184,10 @@ function mail.show_settings(name)
         end
     end
     formspec = formspec .. mail.theme
-	minetest.show_formspec(name, FORMNAME, formspec)
+	core.show_formspec(name, FORMNAME, formspec)
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+core.register_on_player_receive_fields(function(player, formname, fields)
 	if formname ~= FORMNAME then
 		return
 	end
@@ -215,7 +215,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
                 mail.selected_idxs[setting][playername] = mail.selected_idxs[setting][playername] or
                 mail.get_setting(playername, setting)
                 if fields[setting] then
-                    local evt = minetest.explode_table_event(fields[setting])
+                    local evt = core.explode_table_event(fields[setting])
                     mail.selected_idxs["index_" .. setting][playername] = evt.row-1
                 elseif fields["add_" .. setting] then
                     table.insert(mail.selected_idxs[setting][playername], fields["field_" .. setting])
@@ -233,7 +233,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 		return
 
     elseif fields.groups then
-        local evt = minetest.explode_table_event(fields.groups)
+        local evt = core.explode_table_event(fields.groups)
         mail.selected_idxs.settings_group[playername] = mail.settings_groups[tonumber(evt.row)].name
         mail.show_settings(playername)
     elseif fields.optionstab == "1" then
diff --git a/ui/trash.lua b/ui/trash.lua
index eee516f..5508846 100644
--- a/ui/trash.lua
+++ b/ui/trash.lua
@@ -28,14 +28,14 @@ function mail.show_trash(name)
 		for _, message in ipairs(messages) do
 			formspec[#formspec + 1] = ","
 			formspec[#formspec + 1] = ","
-			formspec[#formspec + 1] = minetest.formspec_escape(message.to)
+			formspec[#formspec + 1] = core.formspec_escape(message.to)
 			formspec[#formspec + 1] = ","
 			if message.subject ~= "" then
 				if string.len(message.subject) > 30 then
-					formspec[#formspec + 1] = minetest.formspec_escape(string.sub(message.subject, 1, 27))
+					formspec[#formspec + 1] = core.formspec_escape(string.sub(message.subject, 1, 27))
 					formspec[#formspec + 1] = "..."
 				else
-					formspec[#formspec + 1] = minetest.formspec_escape(message.subject)
+					formspec[#formspec + 1] = core.formspec_escape(message.subject)
 				end
 			else
 				formspec[#formspec + 1] = S("(No subject)")
@@ -49,5 +49,5 @@ function mail.show_trash(name)
 	else
 		formspec[#formspec + 1] = "]label[2.25,4.5;" .. S("Trash is empty") .. "]"
 	end
-    minetest.show_formspec(name, "mail:trash", table.concat(formspec, ""))
+    core.show_formspec(name, "mail:trash", table.concat(formspec, ""))
 end
diff --git a/util/contact.lua b/util/contact.lua
index b890f43..25c5db9 100644
--- a/util/contact.lua
+++ b/util/contact.lua
@@ -12,7 +12,7 @@ function mail.compile_contact_list(name, selected, playernames)
 			if i == 1 then length = l end
 			formspec[#formspec + 1] = ","
 			formspec[#formspec + 1] = ","
-			formspec[#formspec + 1] = minetest.formspec_escape(contact.name)
+			formspec[#formspec + 1] = core.formspec_escape(contact.name)
 			formspec[#formspec + 1] = ","
 			local note = contact.note
 			-- display an ellipsis if the note spans multiple lines
@@ -20,7 +20,7 @@ function mail.compile_contact_list(name, selected, playernames)
 			if idx ~= nil then
 				note = string.sub(note, 1, idx-1) .. ' ...'
 			end
-			formspec[#formspec + 1] = minetest.formspec_escape(note)
+			formspec[#formspec + 1] = core.formspec_escape(note)
 			if type(selected) == "string" then
 				if string.lower(selected) == k then
 					selected = i
@@ -43,7 +43,7 @@ function mail.compile_contact_list(name, selected, playernames)
 		for i,c in ipairs(playernames) do
 			formspec[#formspec + 1] = ","
 			formspec[#formspec + 1] = ","
-			formspec[#formspec + 1] = minetest.formspec_escape(c)
+			formspec[#formspec + 1] = core.formspec_escape(c)
 			formspec[#formspec + 1] = ","
 			if contacts[string.lower(c)] == nil then
 				formspec[#formspec + 1] = ""
@@ -54,7 +54,7 @@ function mail.compile_contact_list(name, selected, playernames)
 				if idx ~= nil then
 					note = string.sub(note, 1, idx-1) .. ' ...'
 				end
-				formspec[#formspec + 1] = minetest.formspec_escape(note)
+				formspec[#formspec + 1] = core.formspec_escape(note)
 			end
 			if not selected then
 				if type(selected) == "string" then
diff --git a/util/init.lua b/util/init.lua
index d5e0560..ce916a6 100644
--- a/util/init.lua
+++ b/util/init.lua
@@ -1,5 +1,5 @@
 -- sub files
-local MP = minetest.get_modpath(minetest.get_current_modname())
+local MP = core.get_modpath(core.get_current_modname())
 dofile(MP .. "/util/normalize.lua")
 dofile(MP .. "/util/colors.lua")
 dofile(MP .. "/util/contact.lua")
diff --git a/util/settings.lua b/util/settings.lua
index 4c21e71..c666ae9 100644
--- a/util/settings.lua
+++ b/util/settings.lua
@@ -74,7 +74,7 @@ end
 function mail.settings.mute_list.check(name, value)
     local valid_players = {}
     for _, p in ipairs(value) do
-        if p ~= name and minetest.player_exists(p) then
+        if p ~= name and core.player_exists(p) then
             table.insert(valid_players, p)
         end
     end
@@ -82,9 +82,9 @@ function mail.settings.mute_list.check(name, value)
 end
 
 function mail.settings.mute_list.sync(name)
-    if minetest.get_modpath("beerchat") then
+    if core.get_modpath("beerchat") then
         local players = {}
-        for other_player, _ in minetest.get_auth_handler().iterate() do
+        for other_player, _ in core.get_auth_handler().iterate() do
             if beerchat.has_player_muted_player(name, other_player) then
                 table.insert(players, other_player)
             end
@@ -95,16 +95,16 @@ function mail.settings.mute_list.sync(name)
 end
 
 function mail.settings.mute_list.transfer(name, value)
-    if minetest.get_modpath("beerchat") then
-        for other_player, _ in minetest.get_auth_handler().iterate() do -- unmute all
+    if core.get_modpath("beerchat") then
+        for other_player, _ in core.get_auth_handler().iterate() do -- unmute all
             if not beerchat.execute_callbacks("before_mute", name, other_player) then
                 return false
             end
-            minetest.get_player_by_name(name):get_meta():set_string(
+            core.get_player_by_name(name):get_meta():set_string(
 				"beerchat:muted:" .. other_player, "")
         end
         for _, other_player in ipairs(value) do -- then mute only players in table
-            minetest.get_player_by_name(name):get_meta():set_string(
+            core.get_player_by_name(name):get_meta():set_string(
                     "beerchat:muted:" .. other_player, "true")
         end
         return true