Retailers' email campaigns using lists of 100 addresses had the highest open rate (38.78 percent) but the third-highest click-through rate (10.67 percent), according to the VerticalResponse Q1 2006 Email Trends Report, Internet Retailerwrites. Campaigns using 100,000 addresses had the lowest open rate (14.41 percent) and the second-lowest click-through rate (4.05 percent). Retailers using lists of 250 email addresses had the highest click-through rate (14.7 percent); lists of 1 million produced the lowest rate (3.09 percent).