Another option is to just mention in the email that it was sent to other people and that nobody should use the "reply to all" option.
Nhọrọ ọzọ bụ naanị ịkọwa na email na e zigaara ya ndị ọzọ nakwa na ọ dịghị onye kwesịrị iji "azịza niile" nhọrọ.