class Net::IMAP

def setquota(mailbox, quota)

[RFC2087[https://tools.ietf.org/html/rfc2087]].
The server's capabilities must include +QUOTA+

===== Capabilities

Related: #getquota, #getquotaroot

in as a server admin for this to work.
+quota+ will be unset for that mailbox. Typically one needs to be logged
along with the specified +mailbox+ and +quota+. If +quota+ is nil, then
Sends a {SETQUOTA command [RFC2087 ยง4.1]}[https://www.rfc-editor.org/rfc/rfc2087#section-4.1] 
def setquota(mailbox, quota)
  if quota.nil?
    data = '()'
  else
    data = '(STORAGE ' + quota.to_s + ')'
  end
  send_command("SETQUOTA", mailbox, RawData.new(data))
end