The election has officially begun in Texas. County clerks have been sending out absentee ballots to those eligible to receive them: Military and overseas voters, as well as the elderly, disabled, and those who will be out of town on voting day.
Here's a guide to absentee voting, and additional information from the Texas Secretary of State's office.
Ballots can be requested until October 30.
Ballotpedia has background on absentee ballot voter fraud, with special attention paid to Texas - of course.