http://www.sos.ca.gov/elections/Outreach/absentee/links/absgde_long.pdfF. How are vote-by-mail ballots counted?
In general, vote-by-mail ballots are counted the same as regular ballots cast
at a polling place. Once it is determined that the signature on the vote-bymail
ballot return envelope matches the signature of the voter on his or her
voter registration card and the voter has not voted at a polling place, the
ballot and the envelope are separated. The processing of vote-by-mail ballot
return envelopes, and the processing and counting of vote-by-mail ballot
return envelopes, and the processing and counting of vote-by-mail ballots
shall be open to the public, both prior to and after the election.
Elections Code § 15101 and § 15104(a)
If the vote-by-mail ballot is challenged, and that challenge is upheld, the
ballot remains in the envelope, is not counted, and the reason is indicated on
the envelope.
Elections Code § 15105 and § 15108
The first results you are likely to hear reported on election night usually
reflect votes cast by vote-by-mail ballot. These, however, are not complete
totals and may reflect only those vote-by-mail ballots returned prior to
Election Day. Those ballots received prior to Election Day can be
“processed” (i.e., verify the signature, etc.) within the seven (7) days prior to
an election. Under no circumstance may a vote count be accessed or released
until the polls close on Election Day.
Election Code § 15101
A substantial number of additional vote-by-mail ballots are returned on
Election Day either to the polling place or to the elections office. These
ballots, because they require the extra handling of checking the voter’s
signature, and ensuring that the voter did not also vote at the polling place,
are usually the last ballots counted, and are not likely to be reported in the
vote totals until after the Election Day.
Elections Code §§ 3017, 3019