This role enables administrators to manage existing mailboxes, mail users, and mail contacts in an organization. This role ...

This role enables administrators to manage existing mailboxes, mail users, and mail contacts in an organization. This role can't create these recipients. Use MailRecipientCreation roles to create them.
This role type doesn't enable you to  manage mail-enabled public folders or distribution groups. Use the MailEnabledPublicFolders and DistributionGroup roles to manage these objects. 
If your organization has a split permissions model where recipient creation and management are performed by different groups, assign the MailRecipientCreation roles to the group that performs recipient creation and the MailRecipients roles to the group that performs recipient management.