Postman butterfly

Why is this. Called a postman butterfly?

Heliconius erato? if not I will have to update my photo as well.

I saw on of these butterflies in Honduras and was told it was a helicopter butterfly.

Usually you cannot determine the subspecies of Heliconius (or some other butterflies as well) from butterfly houses, since you do not know the source where they got them or the exact location where they are originally living. Most of the butterfly houses are provided with pupae from the same (few) sources and give them from one house to the other. I usually call this "pupa incest".

Did you take this with a phone camera- just asking.

It is certainly some kind of Postman, Red Postman or Postman, so, either Heliconius erato OR Heliconius melpomene. You need a clear ventral view to separate them. From an open wing shot you can't separate them. In yours I would slightly tend to Heliconius melpomene, but I am not 100% sure.