Info on Psilocybin and Heat Erowid runs on the donations and memberships of visitors. I think the open question is whether all dried mushrooms can be boiled without significant loss or whether some types react better or worse to this treatment. Sub-boiling or lightly boiling water does not noticably reduce the activity of dried Psilocybe cubensis .
Many people ingest their mushrooms as tea without needing to increase the quantity used.
I know of people who regularly boil their mushrooms for up to 30 mins before drinking the resulting liquid. All fully active. The hotter the water, the better. The water should be at least slightly acidic, but psilocybin is highly water soluable. So, the experience of many people says it works.