Six Christchurch post boxes have been broken into and the mail stolen, in what is being called a targeted criminal activity.
The contents were taken early on Friday morning from post boxes on Hay Street, Opawa Road, Ferry Road, Waltham Street, Selwyn Street and Main South Road.
New Zealand Post spokeswoman Jaimee Burke says they are working hard to make sure those who did it are caught.
"These posting boxes are secure and robust units, so the damage to the boxes indicates tools were used to force entry, we're working closely with the police and the help of the public to ensure that this doesn't happen again," she said.
Ms Burke says they have tried to figure out what has been taken.
"We don't know for certain how much mail has gone missing. Based on normal posting patterns going into a holiday weekend, we suspect it would have been a very light volume."
Jaimee Burke says if people suspect something they posted has gone missing then they need to contact New Zealand Post so the details of the missing item can be lodged.