Magenta went to her mailbox to find a neighbour's letter about her autistic son's "noise."

Last month Brisbane mum Magenta Quinn was awoken at 10.30pm to find three police officers standing at her door.

They’d received complaints of “Sudanese chanting” and showed up to ask some questions.

When the single mum of three explained that her 17-year-old son has autism and occasionally yelped or hummed as a way to calm himself, they apologised for disturbing her and left. Magenta shut the door thinking that was the end of it.

Then, on the weekend, she went to her mailbox and found a soggy, anonymous note that threatened her and her son.

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“When you moved in we heard these strange moaning and shouting coming from your garden every day and night, for which we were concerned may be illegal activities, so we contacted the police who in turn have visited your premises,” the letter said.

“They informed us of your situation that a person in your family is suffering from a mental illness and that was the source of the noise.”

The neighbour then asked for Magenta to “try to limit the amount of time spent in the garden” so they don’t have to listen to the “disturbing” noise daily.

“If this continues at the regular intervals it has been, I intend to make formal complaints against you to council to help resolve the issue.”

Magenta told Mamamia she considered the letter to be bullying and clearly showed a lack of understanding and compassion from the author.

“My first reaction was annoyance and a bit of shock. They sent the police around first, and I get that, I don’t like confrontation either. Surely after that, they could have come and spoken to me, but they didn’t.”

“This is why I’ve done something about it, because what they’ve done is not okay.”

After sharing the note along with a message to the neighbour - who she has no way of getting in touch with - in a community Facebook group, she decided to make the post public.

"While I appreciate the odd noises of a mentally ill person can be disturbing, I can guarantee that you have no clue when compared to living with it 24/7 for 17 years," the full-time carer wrote.

"Having three police turn up at my doorstep at 10:30 at night when I'm new to the area may have made you feel you are avoiding confrontation, but for me it was alarming to say the least.

"Talking with council won't help, he's not a dog, it's a person.

"If you'd like to take him on a holiday so I can get some rest that would be awesome. Otherwise, please feel free to come and chat with me, there's a lot you do not understand."

So far the anonymous neighbour has not reached out to have a chat, but the response from others has been "extremely" supportive.

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Magenta told Mamamia she wished the neighbour had have tried to start a conversation instead of "attacking" her in the hostile letter.

"There are two sides to everything. I'm sure he disturbs him. I've lived with him for 17 years and yes he can get noisy. However, I don't know what their requirements are," she said.

"Even if they weren't comfortable to physically chat with me they could have left their mobile number and I could have text them and we could have started a dialogue, but they gave me no option.

"They absolutely slammed me, they basically told me to muzzle my son and didn't give me a way to come back to them."

She urged anyone facing a similar dilemma to reach out with kindness.

"Don't be quite as judgemental or if you're going to judge, because we all do, just be a little bit more compassionate."