MAILS IN VIRGINIA. The Postmaster-General last evening issued the following orders for mail service in Vir ginia, to commence the Ist of January next: :*."Pittsylvania Courthouse to Lynchburg twice a week: Pittsylvania Courthouse to Danville three times a week; Pittsylvania Courthouse to Glade Hill once a week; Old Paint Comfort to Hampton six times a week ; Fredericksburg, by Chancellorsville, Wilder ness, Locust Grove, Verdiersville and Union ville to Orange Courthouse twice a week ;