A study for Marketing by Nielsen Media Research shows charities are among the biggest offenders, with 33.7% of their mail discarded unseen. Finance firms, however, have improved: 12.5% of their mail was binned unopened, down from 15.5%.
The overall amount of mail disposed of without being opened has barely changed from last year, when the figure was 22%; rates of name and address errors in mailings were unchanged at 4% and 1% respectively.
Overall spend on direct mail was down 10% in the year to June to £1.68m.
Finance firm MBNA remains the UK's biggest investor in the medium, having raised its spend by 1% to £45m.