The principle of a newsletter tool is to create groups of people in order to target people sensitive to your product. Example: There is no point in sending a promotion for 5kg of leg of lamb to people who are vegetarians. In this case, you could create an "all food customers" group and a "vegetarian customers" group.
Therefore, when you make a selection via Interests Centres (see explanation on http://www.simple-crm-support.com/2015/02/comment-ajouter-des-champs-par-exemple.html) or via Big Data Mining (see explanation on http://www.simple-crm-support.com/search/label/Big%20Data%20Mining) you have the possibility to send this selection in an existing group in Simple Mass Mailing or to create a new group :
To learn how to use the Simple Mass Mailing module, please read: http://www.simple-crm-support.com/2017/06/comment-debuter-avec-simple-mass-mailing.html