This role enables administrators to create mailboxes, mail users, mail contacts, and regular and dynamic distribution groups ...

This role enables administrators to create mailboxes, mail users, mail contacts, and regular and dynamic distribution groups in an organization. This role can be combined with MailRecipients roles to create and manage recipients.
This role type doesn't enable you to mail-enable public folders. Use roles of type MailEnabledPublicFolders to mail-enable public folders. 
If your organization has a split permissions model where recipient creation is performed by a different group than those who perform recipient management, assign the MailRecipientCreation roles to the group that performs recipient creation and the MailRecipients roles to the group that performs recipient management.