I've just tested Windows Live admin Center (using my own domain name, I could setup free 500 email accounts, 5GB each, and can chat via msn with hotmail users in other words co branding) where I simply forward the mx to hotmail mail servers.
Things seems to be fine as detected by live admin center, i can chat with my friends on hotmail accounts. fyi im only using mx from Hotmail mail Servers, and i removed the original mx. Funny, is that, I can send email frm hotmail (using my domain name) but I cant receive any reply.
I only use imap and postfix. at this point, I really like the co branding mail from hotmail but at the same time i dont wana mess around with the server configuration (thats why im askin for ur advice :) ), so where did i go wrong?