Privacy Commissioner John Edwards says lessons have been learnt after human error caused a child abuse claimant to receive someone else's confidential information.
A State Services Commission investigation found the mistake of a staff member at the Ministry of Social Development was to blame for the privacy breach, which occurred during the introduction of a new system to speed up institutional child abuse claims.
Mr Edwards said the Ministry's staff were so shaken by the mistake that it would be sure to inform their future work.
"The word mortified was used in the report to describe the reaction of the staff, so certainly I think they're going to take the lessons and internalise them.
"I hope that other agencies will take the report and learn from it and reduce the chances of it happening again."
The Ministry of Social Development received a complaint earlier this month.
Its historic claims team had just launched a new system to get quicker resolution of claims of child abuse in care facilities.
It sent a large number of letters to claimants, which also included financial offers to resolve their claims.
The breach was identified as being due to human error but the report noted the mail was sent out before the ministry was fully resourced to implement the new system.
The Ministry's chief executive Brendan Boyle said it was addressing all recommendations in the report and would make the appropriate changes before more mail was sent.