The 1.3 version of DbMailer for Mac was available as a free download on our website. The program lies within Communication Tools, more precisely E-mail.
From the developer:
DbMailer is a FileMaker Pro plug-in that will enable you to send and receive e-mail from within any FileMaker Pro application. Use DbMailer script guide to access extended e-mail control scripts included in this downloadable extension.
You may want to check out more Mac applications, such as Installer OS X El Capitan, which might be similar to DbMailer.