As it is, "lì mandò" is not grammatically correct. It can either be:
Li mando, meaning I send them (mandare = to send; li = them)
Li mandò, meaning he/she sent them (the accent is characteristic of the past tense)
Lì mando, but this doesn't make much sense as it would mean "there I send", with lì meaning there.
Lì mandò, this doesn't make much sense either unless it's part of a bigger sentence. As it is, it means "there he/she sent".
Where did you find the sentence?