Access Control Defaults


Regardless of the ACL on a mailbox, users who are listed in the admins configuration option in imapd.conf(5) implicitly have the l and a rights on all mailboxes.

Administrators can also see across domains which normal users cannot.


An admin user should not be a normal email account.

Mailbox owners

The user who owns a mailbox folder has additional rights which are set regardless of any additional ACLs. These are:

These are set in implicit_owner_rights of imapd.conf(5).


For all other mailboxes not owned by a user, any user accessing these mailboxes have the following default privileges:

These are set in defaultacl of imapd.conf(5).

Initial ACLs for Newly Created Mailboxes

When a mailbox is created, its ACL starts off with a copy of the ACL of its closest parent mailbox. When a user is created, the ACL on the user’s INBOX starts off with a single entry granting all rights to the user. When a non-user mailbox is created and does not have a parent, its ACL is initialized to the value of the defaultacl option in imapd.conf(5).

Other Implicit Rights

Note that some rights are available implicitly, for example ‘anonymous’ always has ‘p’ on user INBOXes, and users always have la rights on mailboxes within their INBOX hierarchy.