Recently, a few people have given out to me for not answering emails. Why didn't I answer? Generally, because they sent the email to the address I use for MSN Instant Messenger; the address in question hasn't been in working order for about five years.
So, today, I changed my MSN address to firstname.lastname@example.org - my contacts SHOULD be transferred over, but apparently it's not always perfect; if you were on my old list, you might as well add email@example.com.
By the way, Microsoft's page for changing your MSN (now Windows Live) details is one of the worst I have ever seen. Yuk.