Iowa Code § 497.16: Voting by mail.

At any regularly called general or special meeting of the stockholders, a written vote received by mail from any absent stockholder, and signed by that stockholder, may be read in such meeting, and shall be equivalent to a vote of each of the stockholders so signing, provided the stockholder has been previously notified in writing by the secretary of the exact motion or resolution upon which such vote is taken, and a copy of same is forwarded with and attached to the vote so mailed by the stockholder.