NCEA results will be available online from 2pm - 3pm onwards on Thursday.
The Qualifications Authority says 140,000 results were posted in the mail on Wednesday.
Deputy chief executive Bali Haque says the authority does not anticipate demand for results, will cause problems with the website.
He says exams papers will be returned later from 21 January.
National Certificates of Educational Achievement are New Zealand's national qualifications for senior secondary students. The NCEA is part of the National Qualifications Framework.