How come illusive man sends me messages after resigning at the end of mass effect 2?

so i beat mass effect 2 a long time ago, i quit cerberus, and now i have some dlc, and i get a message from the illusive man telling me about the new missions, this doesnt put me back into cerberus does it? or is it supposed to happen either way? and after i beat arrival the admiral said that my ship no longer belonged to cerberus, so i guess im not but still why would illusive man send me the messages?