In the USA, Email’s ROI in 2008 was $45.06 (US) for every dollar spent. Even though it has dropped from $48.34 last year, and is projected to drop to $43.52 in 2009, Email ROI is still by far the best ROI you can find.

Compare email to the ROI of other types of direct marketing:

• Non-Email Internet marketing’s ROI was $19.94 for every dollar in 2008 – 19.97$ projected in 2009
• Catalog marketing was $7.28 in 2008 – $7.25 in 2009
• Non-catalog direct marketing was $15.55 in 2008 – $15.50 in 2009

Those numbers were released in The Power of Direct Marketing: ROI, Sales, Expenditures, and Employment in the US, 2008-2009 Edition from Direct Marketing Association.