Tips to Strengthen Your E-mail Campaigns

Van Diest recommended waiting at least 48 hours before declaring a test winner.

"Remember," she said, "the more you test, the more you'll learn. Be sure to use what you learn."

The most important e-mail metric to focus on is conversion rate, which shows the percent of clickthroughs that resulted in an action, whether that action is making a donation, registering for an event, taking a survey, renewing a membership, etc.