Add default signature for plain-text campaigns

Author: wmnnd

lib/keila/mailings/builder.ex

@@ -144,7 +144,7 @@ defmodule Keila.Mailings.Builder do
   defp put_body(email, campaign = %{settings: %{type: :text}}, assigns) do
     body_with_signature =
       (campaign.text_body || "") <>
-        "\n\n--  \n" <> (assigns["signature"] || HybridTemplate.signature())
+        "\n\n--  \n" <> (assigns["signature"] || HybridTemplate.text_signature())
 
     case render_liquid(body_with_signature, assigns) do
       {:ok, text_body} ->

lib/keila/templates/hybrid_template.ex

@@ -102,6 +102,13 @@ defmodule Keila.Templates.HybridTemplate do
   Powered by [Keila - OpenSource Newsletters](https://www.keila.io/)
   """
 
+  @text_signature """
+  Unsubscribe:
+  {{ unsubscribe_link }}
+
+  This newsletter is powered by Keila: https://www.keila.io
+  """
+
   @spec styles() :: Keila.Templates.Css.t()
   def styles() do
     @styles
@@ -130,4 +137,8 @@ defmodule Keila.Templates.HybridTemplate do
   def signature() do
     @signature
   end
+
+  def text_signature() do
+    @text_signature
+  end
 end