根据 Laohu 的 space 上的文章《美国邮件营销的ROI》介绍，eMarketer 在“Why Retail Loves E-Mail”中披露，在经济下滑时期，零售商加大了向消费者发送邮件的数量。
在另一份报告“Retail E-Mail: Online Marketing Strategies”中，eMarketer引用了美国直复营销协会(DMA - Direct Marketing Association)的数据——每投入$1的商业邮件广告，可产生$43.52的销售额。
Why Retail Loves E-Mail
“E-mail marketing still accounts for only 1.5% of direct marketing budgets in the US,” says Mr. Grau. ——在美国，邮件营销在直复营销预算中只占微小的比例，大约1.5%。
来源：eMarketer 引用：https://www.xiaohui.com/dev/server/usa-email-marking.htm
这里还有一份来自 DMA 网站的报告：《Direct Marketing Ad Expenditures Account for 53% of Total US Advertising Expenditures, DMA's 'Power of Direct Marketing' Report Unveils》，注意报告末尾的小结：
Growth for Interactive Marketing:
Expenditures in the newer online media will maintain significant growth in the coming year. Commercial email will continue to claim the top growth ranking for 2009, while Internet advertising will claim over 15 percent of all direct marketing advertising dollars in 2009.