Download of MassEmail 1.0 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. 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. MassEmail for Mac lies within Communication Tools, more precisely E-mail.
From the developer:
Have you ever wanted to send out a mass mailing to a large group of email recipients? If so, MassEmail will certainly come in handy. Combining the power of FileMaker Pro, Claris Email, and AppleScript, MassEmail quickly makes it possible to send out messages to a long list of recipients with little hassle on your end.
You may want to check out more Mac applications, such as Installer OS X El Capitan, which might be similar to MassEmail.