Downloading Litmus 1.0 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is Avery deGruchy.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The application lies within Communication Tools, more precisely E-mail. The most popular version of the software is 1.0.
From the developer:
Litmus Scope helps you share your email designs and templates. With this application, you can create a clean, web-based version of any email, with desktop and mobile previews. The app is very easy to use, simply drag an email from Apple Mail or Sparrow, on to the Scope icon on your menu bar.
You may want to check out more software for Mac, such as Zimbra Toaster, PageSender or Mail to ToDo X, which might be similar to Litmus.