This question cannot be answered with the information provided.  I do not practice in Alabama and cannot tell you all the nuances of Alabama law.  I assume you are talking about a letter written completely by the person who owns the estate - i.e., completely in his or her own hand and signed by him or her.  If so, you are talking about a "holographic will" if this is the only document in existence or a "holographic codicil" if there is also a will.  I understand that Alabama, like Florida, does not recognize holographic wills or codicils.However, Florida permits a testator to prepare a document called a "separate writing memorandum" to a will.  This document would be like "a signed letter piece of paper" and allows the testator to list people to receive specific personal property.  If the will directs the executor of the will to honor the separate writing memorandum, he or she will honor it.  I do not know if Alabama recognizes a similar type of document, so I suggest you call a probate lawyer in your area to find out if the specific document you describe is valid.