Softbank keeps sending me mails for the old tenants of my current unit.

Hi! The title is self explanatory but I just wanted to ask if who should I contact regarding this? Should I directly call Softbank or the company that manages my apartment? The old tenants probably did not change or updated their address to Softbank, they keep sending me mails stating “Important Notice” it seems urgent so I want to contact someone but not sure who exactly.