I got my welcome message now, with some delay.

Anyway, I see you've already replied over at the 'dot. Yes, the mail was probably spam filtered by hotmail. I found a post on some other forum:

I've found that, for some reason, the final Account Activation email is considered spam by hotmail's junk mail filter.

The empty sender might indeed be the reason for that. We'll have to wait for Myrthos to come up with a mail address to use there.