MarketingSherpa released their 2009 edition of the Email Marketing Benchmark Guide. Here are some of the highlights:

• A down economy means more email – means more competition at the inbox
• Attitude toward email budgets correlates with performance
• To increase opt-ins, offer real benefits – consumers want to opt-in but they want something in exchange
• You can overcome image blocking – good email design can trump image blocking – to an extent

Read the executive summary here.