Are you sure about that? The Secretary of State website makes it seem like they need to be requested:

"Any registered voter may vote using a vote-by-mail ballot instead of going to the polls on Election Day. To request a vote-by-mail ballot for a single election or to request a vote-by-mail ballot for all elections (permanent vote-by-mail voting), follow the simple process described below."

https://www.sos.ca.gov/elections/voter-registration/vote-mai...