Do not mail. Put your ballot in an official ballot box. There is one in the parking lot at the Latah County Courthouse. It must be received by 8pm on Election Day.
Check on the status of your ballot: https://elections.sos.idaho.gov/ElectionLink/ElectionLink/VoterSearch.aspx
If it has not been accepted, contact the Latah County Clerk’s office at once. Elections: Phone: (208) 883-2249