I am signed into LiveMail 2012 with a new MS account name. Replies to emails still come back with original name on them. i.e. I sign in as Mack Smith but emails come back to Kati Work. What do I do?

I am signed into LiveMail 2012 with a new MS account name. Replies to emails still come back with original name on them. i.e. I sign in as Mack Smith but emails come back to Kati Work. What do I do?