I've used ActiveSync to sync my work e-mail on the phone. Everytime I try to send a message, phone displays Sending E-mail Failed. My IT group and LG have not been able to slove this problem.
You did mention that you have already contacted LG but it was no help. In my experience with LG, contacting them again and getting another representative sometimes help. You just need some luck in getting a knowledgeable rep to help you out with your phone's issue. Good luck.