added warning to use old keys

lib/pleroma/application_requirements.ex

@@ -17,6 +17,7 @@ defmodule Pleroma.ApplicationRequirements do
   def verify! do
     :ok
     |> check_migrations_applied!()
+    |> check_welcome_message_config!()
     |> check_rum!()
     |> handle_result()
   end
@@ -24,6 +25,22 @@ defmodule Pleroma.ApplicationRequirements do
   defp handle_result(:ok), do: :ok
   defp handle_result({:error, message}), do: raise(VerifyError, message: message)
 
+  defp check_welcome_message_config!(:ok) do
+    if Pleroma.Config.get([:welcome, :email, :enabled], false) and
+         not Pleroma.Emails.Mailer.enabled?() do
+      Logger.error("""
+      To send welcome email do you need to enable mail.
+      \nconfig :pleroma, Pleroma.Emails.Mailer, enabled: true
+      """)
+
+      {:error, "The mail disabled."}
+    else
+      :ok
+    end
+  end
+
+  defp check_welcome_message_config!(result), do: result
+
   # Checks for pending migrations.
   #
   def check_migrations_applied!(:ok) do

lib/pleroma/config/deprecation_warnings.ex

@@ -55,6 +55,24 @@ defmodule Pleroma.Config.DeprecationWarnings do
     mrf_user_allowlist()
     check_old_mrf_config()
     check_media_proxy_whitelist_config()
+    check_welcome_message_config()
+  end
+
+  def check_welcome_message_config do
+    instance_config = Pleroma.Config.get([:instance])
+
+    use_old_config =
+      Keyword.has_key?(instance_config, :welcome_user_nickname) or
+        Keyword.has_key?(instance_config, :welcome_message)
+
+    if use_old_config do
+      Logger.error("""
+      !!!DEPRECATION WARNING!!!
+      Your config is using old namespaces for Welcome messages configuration. You are need to change to new namespaces:
+      \n* `config :pleroma, :instance, welcome_user_nickname` is now `config :pleroma, :welcome, :direct_message, :sender_nickname`
+      \n* `config :pleroma, :instance, welcome_message` is now `config :pleroma, :welcome, :direct_message, :message`
+      """)
+    end
   end
 
   def check_old_mrf_config do

lib/pleroma/user.ex

@@ -737,6 +737,7 @@ defmodule Pleroma.User do
       {:ok, :noop}
     end
   end
+
   def send_welcome_email(_), do: {:ok, :noop}
 
   def try_send_confirmation_email(%User{} = user) do