Property Manager Is Charging A Littering Fee To The Entire Building, Is This Legal In Nh?

"Hello Residents of 207,

Per my email that I sent out on December 2nd about a $50 fine being issued if trash is being left outside the dumpster, your building was in violation of not cooperating with this matter.

Unfortunately, a mattress and a bed frame was left outside your dumpster today. As a result, I am only issuing a $15 charge, that has been applied to all residents in building 207.

If you are aware of who was responsible for this and have any documentation or evidence, please reach out to me directly. If the responsible party is identified, I will remove the charge for everyone.

Thank you for your understanding and cooperation. Please let me know if you have any questions."

Is this legal in the state of NH?