I don’t know where you live, but if it is in an area where there are a lot of non-English speaking residents (like my suburb) notices in the foyer won’t mean anything to them. A notice in the predominant language or languages may help, or even a photocopied note in that language in everyone’s letterbox. A drawing of what is not acceptable with a big X next to it may also be of use.
Good luck – living with other people can be very trying.