The topic of this master thesis is the issue and organization of group notifying based on the example of volunteers of the city's Red Cross society. Thesis describes the problems of crisis cases that occur after a natural disaster. The concept of organization and organizational structure in both crisis and normal situations is explained The way in which a software solution in the form of a network application can improve the course of crisis resolution and the structure of the organization is described. The practical part includes the implementation of various programming languages and tools into one information system for group notifying of volunteers. The prototype of the organization system is described in detail in the thesis, so that it is as close as possible to potential readers who are not familiar with programming languages and their syntax. The implemented system enables simpler and faster sending of messages via e-mail to a large number of volunteers. With a little desire and will of the volunteers, the system could come to life and help many people to find their way through difficult times more easily and quickly.