Managing Groups in the Outlook Desktop App

Open Outlook.

On the Home tab, choose New Group.

In the "Create Group" window, enter the required information, including Name, Group ID, and Privacy level (Public or Private). Note that you will not be able to change the group ID after you create the group.

Check the subscription box to let members receive the group’s emails in their regular inbox or leave it deselected if you prefer that they access the group’s mail only from the group’s inbox, and then click OK.

Add the members (you aren’t able to add external users at this time), description, and a photo for the group, and then click OK. You can add members after the group is created, as well.

Click OK. You will see your newly created group in the left navigation pane and a "Welcome" email in your group’s inbox.

Open Outlook.

Under Groups in the left navigation pane, select your group.

On the Groups ribbon, select Group settings → Add Members.

In the Add people box, search for people within your organization either by their full name or email address, and then select the names to add.

You can also, select Invite others from the Group settings window.

Do one of the following:

• Select Copy to copy a link to the group to your clipboard. Paste the link into a message to share it with others.

• Select Email to open a compose window with a link to join the group.

Finish composing the mail and click Send.

Click OK.

Open Outlook.

Under Groups in the left navigation pane, select your group.

On the Groups ribbon, select Add Members.

In the Add people box, enter the email address of the guest and press Enter. Red text reminds you that guests will have access to group content.

Select OK.

On the Home tab, select Browse Groups.

Enter a group name in the search box or scroll the list to find the one you want.

Click Join. If the group is private, a request will be sent to the group’s admin, who can accept or decline your request.

If you receive an email message from a group that you are not a member of and decide to join the group, select Join on the group header in the right corner of the reading pane. 
If the group is private, you will see Request to Join instead, and will be asked to provide a reason for joining.

Wait for your request to go through, or for the group’s administrator to add you if you’re trying to join a private group.

Once you have joined the group, you will see detailed membership status as well as a shortcut to navigate to the group’s inbox.