# File lib/action_mailer/vendor/tmail-1.2.3/tmail/mailbox.rb, line 217
    def UNIXMbox.new( filename, tmpdir = nil, readonly = false )
      tmpdir = ENV['TEMP'] || ENV['TMP'] || '/tmp'
      newobj(filename, "#{tmpdir}/ruby_tmail_#{$$}_#{rand()}", readonly, false)
    end