The offending was alleged to have occurred in 2014 and 2015, after Tucker left Custom.
The tribunal ruled Tucker had committed disgraceful misconduct in sending the packages, but found the allegation involving the headless rat was not proved.
Tucker, who owned Netrealty and represented himself during the hearing, was discharged without conviction in 2015 in Auckland District Court after he admitted sending a package containing what was believed to be human excrement and broken glass to Beard.
Beard told last year's hearing he began opening the courier-type package "but as I started I smelled something vile".
He took it to police and opened it outside with an officer using protective gloves.
"Inside was what looked and smelled like human faeces. I was gagging over the side of Auckland Central Police Station."
Tucker argued the package was first sent to him and he was simply returning it.
But he "vehemently denied" sending a further series of packages to Wills and Beard, including the decapitated rodent, which leaked brown liquid over a Custom staff member's dress.
"He said he was a life member of the SPCA, and found what had been done to the animal abhorrent," the tribunal decision recorded.
Tucker did accept leaving a derogatory voice message on Wills' phone, referring to his old boss as a "c**k-sucking f*****t".
But he claimed he was stressed at the time, having been pepper-sprayed by his former partner that day, who had then tried to "frame him as the attacker" when police were involved, the decision said.
He denied verbally abusing Wills in Ponsonby in March last year by saying, "Found your balls yet you gutless piece of shit", though the tribunal ruled this did occur.
The tribunal also ruled Tucker had sent a series of anonymous letters to Custom clients, bad-mouthing the firm with disparaging claims about its ethics and sales record.
It found Tucker's actions "would reasonably be regarded by agents of good standing, or reasonable members of the public, as disgraceful".
Tucker appealed the tribunal's ruling to the High Court, telling the Herald last year the complaints against him were without merit and saying he had practised real estate with honesty and integrity for 20 years.
He argued he had not sent the packages, and it was possible someone else had done so in order to frame him.
But in a just released decision, High Court Justice Sarah Katz said there was "ample circumstantial evidence" to support the tribunal's decision against Tucker.
"It is clear that the sender of the parcels must have felt a high degree of animosity," she said.
"The only person known to have had a history of animosity towards both men, as illustrated by the (now) undisputed facts that I have outlined above, was Mr Tucker.
"The alternative scenarios advanced by Mr Tucker are simply implausible and are not supported by the evidence."
Cancellation of Tucker's license was an appropriate penalty, Justice Katz ruled.
