Not so - you can hand deliver it to your local Registrar of Voters before the election or to any polling place on Election Day. I've done it myself many times, just to avoid the possiblity. Now I just vote at the polling place, so certain am I that the Democratic Party here in California is tampering with absentee ballots.
Don't listen to the advice here -- you are in danger of having your ballot tossed out!
Read this from the Tennessee Election Commission regarding absentee ballots:
10. Can the ballot be hand delivered?No. The by-mail ballot must be received by the county election commission office through the postal mail.