Before Michael Winter could open his mail, he was shocked by what he found on the envelope.
"You know they have no right," said Winter after finding his social security number printed on the front of an envelope mailed to him from Anthem Blue Cross.
The number was printed just above his name next to the words "Priority Code."
"My name, Michael B. Winter, my Hartford Street address and my area code, it is all there," said Winter.
Privacy rights expert Beth Givens says that's been against California law since 2004.
"This is such a surprise to us, I was truly shocked," said Givens, the executive director of the Privacy Rights Clearinghouse in San Diego.
Givens says she has notified the California Attorney General about the letter. She says the law is designed to protect consumers from identity thieves.
"The social security number is the key to opening up a new credit account and crooks have learned this," said Givens.
Anthem Blue Cross issued a statement concerning the 37,900 mailings that went out to Medicare Supplement members.
Highlights from the statement include: "We immediately suspended all mailings and implemented processes to prevent this error from happening again… There is no indication that any information has been used in a way that is detrimental to our members… We are in the process of sending courtesy notices to the affected members along with the offer of free credit monitoring services… We apologize for this error."