Iona Derman, 72, is speaking publicly about an email that exposed personal details and demanded she stop posting active real estate listings on her Instagram account, SF Daily Photo. The sender has not been identified.

The email arrived last May from a Yahoo account using Derman’s name. It listed her past homes, phone numbers, her husband’s name and her education, as well as the address of her daughter and son-in-law. Derman complained to Yahoo, which said it would investigate; she later received little detail, and a message she sent to the account bounced back.

Derman started SF Daily Photo about a decade ago as a retirement project. The account, which takes a preservationist view of mostly San Francisco properties, has more than 60,000 followers. Lawyers for Compass and Vanguard had previously sent cease-and-desist letters seeking removal of listing photos. Derman said she has removed posts or pictures when agents or owners asked. She suspects an agent sent the email, but has not established who did.