Strange Mail

Less than a week in our new house and it's already clear something strange is going on with the mail. The previous owners lived here for 11 years and have set up mail redirection, so we're not getting any mail for them, but we are receiving letters addressed to people we've never heard of. People who can't have lived here for at least 11 years. There's been a lot of "return to sender" going on, but eventually something is going to turn up without a return address and I'll have to choose to open it, or bin it.