When submitting a document for review by e-mail, don’t assume that all reviewers will see additional information that you may have provided in the body of the accompanying e-mail.
I have learned through bitter experience that a contact person will often download the attached document for review and send it to reviewers in their organization without forwarding the accompanying e-mail that I sent.
To solve this problem, on the top of the first page I write an explanation paragraph highlighted in yellow (to differentiate it from the text). I include all pertinent information that is not contained in the body of the document such as why certain sections may be incomplete, questions, and if it is a first draft I explain that the English will be further polished in additional drafts. I always finish with a list of open issues, material that I need from them, and a request to use Track Changes when making changes.
Remember that if you have done the project on an outsource telecommuting basis you may never even have met some of the people who are going over the document, and document will have to speak for itself.