Outlook Groups for Business

Hello,

I am having some problems with the group functionality within outlook

we create groups for each separate job we do and have about 1000 different groups, what I am looking to do is have a group that does not automatically include everyone in the company when it is created, but still have someone be able to join the group without asking permission from an administrator.

Currently everyone is included in every single group, unless you manually opt out so you get like 200 emails a day, my IT guy says that this is the only way for it to work but that seems crazy to me.

Thanks,