Sending drugs and weapons through the post might appeal to some criminals, but they won't necessarily reach their target.
In the past 17 months, 75 items have been caught by New Zealand Post and opened as suspicious.
Most of those items - including drugs, guns and a knife - were reported to police, detained or destroyed.
There were 43 interceptions of cannabis. Ecstasy, cocaine, methamphetamine, ritalin, valium and some unidentified pills and powders were also seized - as was some icing sugar that was mistaken for drugs.
Nine weapons were also intercepted.
The packages were revealed to The Dominion Post under the Official Information Act.
New Zealand Post spokeswoman Jaimee Burke said the postal service was responsible for scanning and identifying mail items transported domestically, and Customs dealt with international mail.
"New Zealand Post takes security very seriously and assists Customs and the police in their investigations. Any suspected illegal items found in the post are passed to the police."
Seized weapons included two shotguns, a .22-calibre rifle, a knife, two airguns, a replica antique pistol and an antique air rifle.
Detective Senior Sergeant Tim Leitch said illegal items found in the mail by New Zealand Post had led to investigations and arrests.
With drugs cases, the sender's and recipient's names, if provided, would often be the starting point of an investigation.
"We do, from time to time, have cases referred to us by New Zealand Post. I can think of one we dealt with . . . that was class C ecstasy mimics that were being sent from Blenheim to Wellington."
After an investigation, a person was convicted and jailed. "That was a guy we weren't aware of. Sometimes it ends up as a prosecution; sometimes it doesn't."
Postal guidelines prohibit specific items being sent in the mail. There are penalties for sending prohibited items under the Postal Services Act, the Civil Aviation Act and other legislation.
- © Fairfax NZ News