REaD Group released the findings as part of its annual DM and suppression report card for 2008, based on analysis and segmentation of the group's total suppression activity over recent months.
Echoing last month's IPA Bellwether Report, which revealed a 12% decline in DM spend for Q4 last year, the REaD Group estimates overall DM volumes declined by an average of 8.5% across all verticals in 2008.
The financial services sector suffered a 29% drop in volume from approximately 1.3bn items at the end of 2007 to around 0.92bn by December 2008.
There were some modest volume gains amid the slew of sectoral DM contractions. REaD estimates charity mailings grew by 8%, mail order rose 7%, while government and utilities remained unchanged from 2007 levels.
Mark Roy, CEO of The REaD Group, said: "The proof is in our figures, unfortunately -- mailboxes and some companies' coffers were noticeably emptier last year.
"But while marketing budgets are being slashed across the board, our analyses and ongoing discussions with clients both indicate that marketers are favouring a combination of DM and digital to spearhead their multi-channel campaigns, which bodes well for DM during the current recession."