Sometimes data collection requirements demand that data be collected in a short time period to study time-sensitive issues. Web-based data collection is particularly well suited for such data collection efforts specially if the target population has easy access to the Internet. In this study we report on 12 randomized trials where the data collection had to be completed within a 120 hour period in two large state Universities. Each university had six trials spread over a period of 12 months. The data collection protocol involved sending an invitation to the subjects followed by a reminder 24 hours after the delivery of the invitation e-mail. In one university the e-mails were signed by an official within the university whereas in the other university the e-mails came from a person outside the institution. Data collection was completed rapidly in the case where the e-mail signatory was within the institution with 96% of the data being collected within 24 hours. Data collection rate was slower in the case of the university where the e-mail signatory was from outside the institution with only 67% of the data being collected within the 24 hours. This suggests that in time-sensitive data collection situations where the data needs to be collected rapidly it is more likely that the data collection effort would be successful if the recipients see the e-mails coming from someone in their own institution. It is likely that there is greater credibility attached to one’s own institution as opposed to an external data collection agency. This finding suggests that it is preferable to have e-mails originating from recognizable sources rather than sources unknown to the recipients. This is important in the age of increasing “spam” e-mails that populate e-mail boxes. Future studies need to take this into account when designing Web-based data collection efforts.