Do you need to be an outlook contact to be part of an email group?

I want to be able to set up  number of mail groups (for different age groups at a junior football club) but I don't want to import all of the email addresses into my address book as specific contacts. However if I create a group in Outlook.com and then paste the email address into it and then save it I get the message that there are no contacts in this group! How can I create mail lists/groups where I don't have to have all of the email recipients set up as my contacts as I have over 300 members of the club that I do not want set up with my own personal contacts?