بسم الله الرحمن الرحيم
Q: What is the ruling on leaving zakatul fitr with a neighbor (authorizing him to give it away on one’s behalf) til the poor person comes (to obtain it)?
A: It’s permissible for an individual to leave it with his neighbor while saying to him this is designated for so and so, and when he comes the neighbor gives it to him. However it must reach the hand of the poor person before the eid prayer due to him being an authorized agent of the giver of it. As for if the neighbor is authorized by a poor person, by the poor person saying fetch the zakatil fitr from your neighbor, in this case it is permissible for it to remain with the authorized agent (of the poor person) even if the people exit from (completing) the eid prayer.
Translated by Najeeb Al Anjelesi
Source: فتاوى في احكام الزكاة