Umbrella is the name of a software-program that can be used to keep information about customers/patients/clients.
The unique part is that these customers can also be given an appointment in the agenda. After that an invoice can be generated if this is required.
Besides invoices, also normal documents can be generated for the customer. Every document can be printed out directly or send to the e-mail address of the customer.
Because of the e-mail functionality, the program can also be used to send e-mail newsletters / mailinglists.