Yes. And yes! All early ballots are required to be placed into a signed Affidavit envelope. Each one of those envelopes is scanned and verified by a person at the Recorder's Office who has been specially trained in forensic signature verification. These verified ballots are then processed and counted. The results are released one hour after the polls close on election night. If the signature doesn't match, the Recorder's Office will attempt to contact the voter.
It is very safe to vote early by mail since the signature match is done for every ballot. Voters can drop their voted ballot in the mail, bring it to the Recorder's Office or use one of the secure and convenient ballot drop boxes located around the County. A list of those locations is posted on the county website.