From a technical point-of-view it is possible to use reproductions, such as faxed or emailed images, to conduct a preliminary examination of the material. In fact, it is possible to do a ‘complete’ examination and evaluation with such materials, but it places significant limitation on the result. It is definitely not recommended. Faxing, or more often emailing, images of documents may expedite the process slightly, but it is very important to understand that doing so has a significant downside.
Original items are always recommended for this type of work. The time spent in shipping the originals for examination is well worth it to ensure the best possible work gets done.
The Bottom Line: Any reproduction, including a fax, photocopy or PDF, is a somewhat limited representation of the original item. The degree of that limitation will vary from one instance/item to the next and may depend on what aspect of the document is in question. However, the results of any (preliminary) evaluation done using reproductions is unlikely to reflect the outcome of work performed on original items. In the event that a (preliminary) assessment is done, the resulting opinion must be expressed in a manner that reflects those limitations or qualifications.
Whether or not that will suffice for the intended purpose is something the client must decide.