Notwithstanding any other provision to the contrary, no member shall vote by proxy on any matter submitted by mail to all members of a credit union in a written ballot pursuant to Chapter 5 (commencing with Section 7510) of Part 3 of Division 2 of Title 1 of the Corporations Code, and the powers of any previously issued or outstanding valid, revocable proxy are suspended when any matter is submitted by mail to all members in a written ballot pursuant to Chapter 5 (commencing with Section 7510) of Part 3 of Division 2 of Title 1 of the Corporations Code.