Downloading GroupsPro 5.6.1 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. This Mac application was originally designed by Demodit GmbH. 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.
From the developer:
GroupsPro lets you manage contacts, contact groups, and create mailing lists for mass email. It is an excellent way to create and organize groups of contacts and create mailing lists. A mailing list contains members of groups or individual recipients.
You may want to check out more software for Mac, such as GroupsPro Lite, which might be similar to GroupsPro.