35 Miss. Code R. § 11-29-205
When an appeal or other document is required to be filed with the Review Board within any number of days, the day of the act, event, or default from which the designated period of time begins to run shall not be included. The last day of the period so computed shall be included unless it is a Saturday, a Sunday, legal holiday, or any other day when the offices of the Agency are in fact closed, with or without legal authority, in which event the period runs until the end of the next day which is not a Saturday, a Sunday, a legal holiday, or any other day when the office of the Agency is closed. Legal holidays for the Agency are found at Miss. Code Ann. § 3-3-7(1). Mailing does not constitute filing, and the time period within which the appeal, objection, or other document has to be filed is not extended because of mailing.
35 Miss. Code. R. § 11-29-205