Tex. Election Code § 251.007: TIMELINESS OF ACTION BY MAIL.

When this title requires a notice, report, or other document or paper to be delivered, submitted, or filed within a specified period or before a specified deadline, a delivery, submission, or filing by first-class United States mail or common or contract carrier is timely, except as otherwise provided by this title, if:

(1) it is properly addressed with postage or handling charges prepaid; and

(2) it bears a post office cancellation mark or a receipt mark of a common or contract carrier indicating a time within the period or before the deadline, or if the person required to take the action furnishes satisfactory proof that it was deposited in the mail or with a common or contract carrier within the period or before the deadline.

Amended by Acts 1987, 70th Leg., ch. 899, Sec. 1, eff. Sept. 1, 1987.