I'm having the following problem:
I am an early user of BTC Guild (< 1000) and I did not set an email address.
I want to change my wallet address, but it says I have to confirm it by email.
So I went to set an email... and it says I have to confirm it by email.
How can I confirm my email by email when I have no email?

I think I found the problem, some old accounts had the email field as empty, rather than NULL. Try again and it should work
.