Include email procedures and limits in advertisements. For example, indicate how frequently e-mail is checked and provide approximate response times. Specify what kinds of questions may be answered by email. For example, some questions require photocopies of pages from reference works and will need to be mailed. E-mail can be a little less reliable than surface mail.
Servers go down.
Messages get lost. Include a reference questionnaire in any advertisements. There is increasing concern that libraries need to be active in promoting information literacy. We must not only provide patrons with information but teach them to evaluate that information. The DigREF listserv has recently been the site of a discussion about how much bibliographic instruction can or should be done via email.