class Net::IMAP

def getacl(mailbox)

[RFC4314[https://tools.ietf.org/html/rfc4314]].
The server's capabilities must include +ACL+

===== Capabilities

Related: #setacl, MailboxACLItem

containing objects of MailboxACLItem will be returned.
along with a specified +mailbox+. If this mailbox exists, an array
Sends a {GETACL command [RFC4314 ยง3.3]}[https://www.rfc-editor.org/rfc/rfc4314#section-3.3] 
def getacl(mailbox)
  synchronize do
    send_command("GETACL", mailbox)
    clear_responses("ACL").last
  end
end