# File lib/mail/network/retriever_methods/imap.rb, line 95
    def delete_all(mailbox='INBOX')
      mailbox ||= 'INBOX'
      mailbox = Net::IMAP.encode_utf7(mailbox)

      start do |imap|
        imap.select(mailbox)
        imap.uid_search(['ALL']).each do |message_id|
          imap.uid_store(message_id, "+FLAGS", [Net::IMAP::DELETED])
        end
        imap.expunge
      end
    end