YES!  ALWAYS do this. 

  We only take research orders by email and we addendize our entire chain of email correspondance to each of our reports, and we always ask for complete clairty from our clients in writing prior to beginning any research. 

  BUT, be sure to include both the effective date range of your research, AS WELL AS the dates during which the research was conducted.  This can help to limit your liability in two ways:  (1) disclosing that you did not search outside of a particular date range for any recorded items and (2)  indicating the status of the records for the day or days which you did the research (this could come in handy should a County-side indexing error occur and be subsequently corrected to your disadvantage).

  Being upfront and clear about the nature, scope and methodology of your research should be a priority for any abstractor.  This serves as a market advantage for you by telling your clients that you are aware of and fully understand the complexities of the various public records systems, while alerting them beforehand to potential pitfalls, including possible misunderstandings, that public records errors could become. 

  Clarity, full disclosure, transparency, honesty and a bit of wordiness are the best ways that you can protect your interests AND your clients' interests.