E-mail is a common invitation mode for Web surveys. This invitation mode is cheap, is easy to automate and personalize, and provides easy access to the survey (a clickable URL). However, there are a growing number of problems with e-mail as an invitation mode, including concerns about spam, the rapid turnover (churn) of e-mail addresses, the fact that many sample frames do not contain e-mail addresses, privacy concerns about providing e-mail addresses when solicited, and the inability to deliver a prepaid incentive.