This is likely the MEA (Marin Energy Authority) or MCE (Marin Clean Energy). Many folks in Marin County are wanting to opt out and stay with PG&E (I did) and they're probably trying to get you to opt back in. 415 covers much of the SF Bay Area.
Many people in Marin County and Richmond are opting in to MEA and getting away from PG&E, MEA isn't trying to get anyone to opt back in. I got a call from them, they were polite & professional. MEA was created by and is regulated by state law, it has to & does follow what the law mandates.