Explanation/Reference:
Explanation:
For each private profile, Database Mail maintains a list of users that are permitted to send e-mail using that profile. Public profiles are available to users or roles in the msdb database who are also members of the DatabaseMailUserRole.
By default, a profile is private, and no users are granted access to the profile. To make the profile public, grant access to the user 'public' or the user id 0.
Note: Profiles are either public or private. A private profile is accessible only to specific users or roles. A public profile allows any user or role with access to the mail host database (msdb) to send e-mail using that profile.
References: https://technet.microsoft.com/en-us/library/ms189879(v=sql.105).aspx