title: Elm send message to mailbox in update function
body: <p>I've the following Action handler in my update function of Elm StartApp MUV framework.</p>
  
  <pre><code>signupAlertMailbox : Signal.Mailbox String
  signupAlertMailbox =
    Signal.mailbox ""
  
  update : Action -&gt; Model -&gt; (Model, Effects Action)
  update action model =
    case action of
      Submit -&gt;
        let isInputValid = Dict.foldl (\fieldName fieldState validity -&gt; if validity
                                                                  then (fieldState == IsOkay)
                                                                  else validity)
                                                                  True model.inputState
            rnd = log "Input valid" isInputValid
        -- in (model, Effects.none)
        in if isInputValid
              then (model, Signal.send signupAlertMailbox.address "Oh snap! Change a few things up and try submitting again."
                                  |&gt; Effects.task
                                  |&gt; Effects.map (always Submit))
              else (model, Signal.send signupAlertMailbox.address "Well done! All input correct!"
                                  |&gt; Effects.task
                                  |&gt; Effects.map (always Submit))
  </code></pre>
  
  <p>Upon Submit action, I can see the log message in browser console, but no message is being sent to signupAlertMailbox. Please help me with this issue.</p>
  
  <p>-- Edit</p>
  
  <p>The StartApp wiring up code as requested in comment below:</p>
  
  <pre><code>import StartApp exposing (start)
  import Time exposing (every, second)
  
  import Pages.Signup.Model
  import Pages.Signup.Update exposing (signupAlertMailbox)
  import Pages.Signup.View
  
  app =
    start
      { init = Pages.Signup.Model.init
      , view = Pages.Signup.View.view
      , update = Pages.Signup.Update.update
      , inputs = []
      }
  </code></pre>