Patching was emotional after learning the email was intended as a curse.
"That has just caught me off guard. I don't even know what to do with that - it's nasty," she said.
The dispute only brewed once Patching gave notice to move out after three-and-a-half happy years in the rental.
Patching accused Zhou's team of arranging viewings for new renters at short notice without first checking the time was suitable.
She said Zhou's behaviour forced her to instead arrange the end of the tenancy directly with the rental property's owner, "who was great".
Zhou denied being difficult and claimed Patching cancelled viewings at the last minute when prospective tenants had already arrived.
Patching said she tried to complain about Zhou without luck.
"I've just discovered there is no governing body for property managers.
"I rang the Tenancy Tribunal and they said unless they've breached the (Residential Tenancies) Act, you can't do anything, they can treat you however they like."
Patching claimed she only found out Zhou was holding an open home for new tenants at her rental when a friend saw the advertisement online.
Under the Act both parties need to agree to a viewing time.
The rental owner then approached Patching directly and the pair amicably arranged viewing times and a plan to move out, Patching said.
Zhou disagreed, claiming Patching agreed to the first viewing in a text message and was given ample notice for the second viewing.
She said Patching barred access to the viewings as a bargaining chip to force Zhou to agree to end the tenancy early and save money - a claim Patching denies.
Zhou said she did everything according to the Residential Tenancies Act and treated Patching with "great respect".
She never intended for Patching to see the "B****, you go to hell" comment because she wrote it in white ink as a hidden curse.
"When they treat me like that, of course I don't feel balance, everyone's got feelings," she said.
The pair's stoush comes as calls grow louder for property managers to be regulated.
The industry has been criticised over stories about managers charging fees to process applications faster and asking to see tenants' bank statements to judge whether they waste too much money on fast food.
In September, the Real Estate Institute launched a campaign urging the Government to review the property management industry and announce reforms before the 2020 election.
About 70 organisation are now supporting the campaign, including tenancy support groups, real estate agents and even property managers.
Property managers managed 184,000 homes, or about one-third of all Kiwi rental properties, the REI estimated.
It meant they had keys and personal information, billions of dollars of housing and millions in rent and bond money in their care.
Yet they didn't need a licence or any kind of accreditation, REI chief executive Bindi Norwell said.
All a person needed to do to become a property manager was say they were one.
"We strongly believe regulation is required to create an industry where all property managers operate ethically and with honesty and transparency."
