Speaking of Google, every mailbox I have is subscribed to a dozen Google Groups full of Arabic-language spam. These are mailboxes on my own domains, that don't have Google Groups or Google Account accounts. Anyone can add you to a group and start spamming you through Google, repeated "report this group as spam" reports don't stop new mails from arriving, and the only way to unsubscribe is to create a Google Account with that mailbox then leave the group.
