Sgt. Ken Harrington says thieves targeted 53 individual mail boxes in Oliver, and there are also reports of theft from mail boxes in Cawston, Keremeos and Kaleden over the past three weeks.
Theives are taking personal mail, which could include credit cards, drivers licenses or passports, he said.
"It is concerning. Our community, our society is generally aware of what damage can be done by identity theft," said Harrington.
A spokesperson for Canada Post says it will add reinforced locks and anti-pry bars to the mail boxes that were vandalized.
The post office also recommends that people retrieve their mail frequently to reduce occurrences of theft.
News of the thefts comes after Canada Post announced plans to replace all remaining home delivery of mail with super mailboxes over the next few years.