In every appeal, except those withdrawn, the chairman shall prepare a written decision which shall be sent by certified mail, return receipt requested, or first class mail, whichever the commissioner determines to be most appropriate, to each interested party at the last address of each according to the records of the department of employment security. The decision, except one on an appeal dismissed for lack of prosecution or defaulted for failure to attend, among other necessary things as determined by the commissioner, shall: set forth all the material findings and specific provisions of law necessary to support the conclusions; identify the interested parties and the account, whether fund or employer, to which benefits will be charged, if allowed; identify the week or period during which benefits are denied; identify the first week and subsequent period with respect to which benefits will be paid, if allowed; determine all things necessary to finally dispose of the case; and identify the members of the tribunal.