First Class is an email and "black-board-like" system used by University of Maine Orono. It should be phasing in the next couple years (~2018). If students don't need First Class class resources, it is recommended they use maine.edu GMail instead.
"First class client cannot be opened because it's from an unidentified developer. Your security preference only allows downloads from the mac store and identified developers."
OS X 10.10 or 10.11
OS X 10.12
Gatekeeper in OS X 10.12 no longer has the option to Allow from Anywhere, so it requires software to be signed. (The client available at https://umaine.edu/it/software/firstclass/ is not a signed version). Users can get a signed version of the client direct from OpenText FirstClass.
FirstClass Desktop Client, MAC OS X Edition