"What we're just wanting is a call-out to members of the public, especially in the Aramoho area, to check on mail they've sent in the last two to three weeks. We're trying to determine or identify people that have had mail taken."
Mr Brunger said credit card or debit details found in the mail had been used to commit fraud.
"Some people have been posting direct debits that disclose their bank details and credit card information."
Mr Brunger said he believed multiple people had fallen victim to the crime.
-Anyone who believes they may be a victim or who has information can call Constable Jonathan Robertson-O'Byrne at Whanganui Police Station on 06349 0600.