Web-based surveys are increasingly used in evaluation practice. To our knowledge, there are no guidelines for calculating outcome rates using newly available tracking methods. In a recent study, up to five recruitment e-mails were sent using an e-mail marketing service: a primer, an invitation with a survey link, and three reminders. Hard and soft bounces and opened e-mails were tracked. Outcome rates varied as a function of decisions made regarding these data. We suggest that several outcome rate calculations be presented to assist the reader in assessing these important measures of study quality.