Mano serves as the third door of action (along with body and speech) and as the sixth internal sense base (along with the five physical sense bases); as the mind base it coordinates the data of the other five senses and also cognizes mental phenonema (dhamma), its own special class of objects.
However, to translate 'mano' exclusively as 'intellect', as Thanissaro does, does not fit all dhamma teachings, especially 'mano' as a sense organ