An Auckland real estate agent who mailed poo to a rival agent has been discharged without conviction.

Grant Campbell Tucker, 58, a director of Netrealty, appeared for sentence in the Auckland District Court on Tuesday after pleading guilty to posting a noxious substance.

The recipient of the package, David Beard, the lawyer of Tucker's former employer Custom Residential, tendered a victim impact statement that detailed the impact on staff and the financial loss he had suffered because of the offending.

Judge Claire Ryan said Tucker posted the noxious substance on March 6, 2014, an offence carrying a maximum penalty of a $5000 fine.

The judge said the offending occurred after Tucker fell out with his former employer, John Wills, the director of Custom Residential.

Tucker left the firm after the company settled a dispute with another agency that reduced his commission on a house sale by 45 per cent.

Tucker subsequently took successful action against the rival real estate agent and his former employer.

"Bad blood arose, things were said that shouldn't have been," the judge said.

"You decided you'd be happy with an apology but never received it."

During the employment difficulties, Tucker's relationship with his partner broke down and police became involved after he was pepper-sprayed.

In the middle of all this, Tucker's sister found a glass jar in his letterbox containing faeces with Tucker's name on it.

Tucker photographed the jar and sent it to police who responded with a letter that began "That is terrible...".

Police did not take further action but when Tucker learned he had been trespassed from his former employer's premises he became convinced they had sent the poo.

He wrapped up the jar in bubble wrap and sent it to the real estate agent's lawyer's office with a note on his letterhead saying it was to be returned to the "good people" from whence it came. ​

The judge said sending the jar in the mail was "fraught with danger" and it broke in the post.

"Now the package was not only offensive but dangerous with broken glass and a vile smell."

Beard took the parcel to police after he noticed the odour.

The parcel was opened by police outside the station and Beard "became violently ill and vomited over the balcony of the Auckland Central Police Station", the judge said.

He had tears running down his face​ and later said Tucker had "tried to turn his place of business into a sewer".

"He was genuinely fearful of what you would do next."

Tucker's lawyer Ron Mansfield said the affair had damaged his client's reputation.

Due to the oddity of the case, the media's interest was "beyond that which would be expected for offending of this level", Mansfield said.

Judge Ryan said the act was impulsive and stupid but the consequences of a conviction would outweigh the gravity of the offending.

She awarded him a discharge without conviction, contingent ​on him paying $750 in emotional harm reparation to the lawyer and $750 to charity