Fix quoted-printable subject question-mark not being encoded

Fix #396

script/mail_new_activity.rb

@@ -12,7 +12,9 @@ class String
     s = [self].pack("M")
 
     if encoded_word
-      s.split(/\r?\n/).map {|l| "=?UTF-8?Q?" + l.gsub(/=*$/, "").tr(" ", "_") << "?=" }.join("\n\t")
+      s.split(/\r?\n/).map {|l|
+        "=?UTF-8?Q?" + l.gsub(/=*$/, "").gsub('?', '=3F').tr(" ", "_") << "?="
+      }.join("\n\t")
     else
       s
     end

spec/scripts/mail_new_activity_spec.rb

@@ -0,0 +1,7 @@
+require_relative '../../script/mail_new_activity'
+
+describe 'EmailSender' do
+  it "encodes text as quoted printable" do
+    expect("Why Use Pointers?".quoted_printable(true)).to eq("=?UTF-8?Q?Why_Use_Pointers=3F?=")
+  end
+end