Welcome to the latest edition of the RGM Inbox. For this instalment, we check out four singer/songwriters. Two are still at the start of what will be successful careers; one has an Ivor Novello award on the shelf, while our final artist has sold millions of records and earned multiple Grammy awards but is still probably best known for his skills as a guitarist. They may work in a range of genres, but the one thing they all have in common is impressive new music to share.