Unable to login because of (not really) invalid mail address

For serveral months now, I have been unable to log into facebook. My account still exists, it's not disabled, my mail address works (I regularily get "x added you as a friend" and similiar messages), I didn't forget my password.

If I try to login: Incorrect Email/Password Combination

If I try to reset the password: Invalid Email

If I try to fill out the support form: Invalid Email

If I try to use a different address to fill out the support form, I get an automated email that says I have to verify that I own the account by replying with the mail address associated with the account.

If I reply from my account address, I never receive a reply (probably they block it even on this level), if I reply from my other address, I never receive a reply (probably because it's not associated with my account and no one even bothers to read it).

Every few weeks I repeat the above steps, but it's always the same.

Point is, it's not invalid! I get facebook notifications! I just can't answer them. Because I can't log in. By now I even get mails from facebook going "Oh, you haven't logged in for a while. You have X friend invitations and Y messages waiting". They send me mails to that address, but they claim it's invalid.

Since my girlfriend has the same problem, I think facebook just invalidated the whole domain - all addresses from that domain (mailnull.com btw) are invalid. That's okay, actually, if they don't want people to register with spam-protection, that's their right. But I just wish they would make it impossible to register, not impossible to login if you already are registered. It would be okay if they told me to choose another address. It would even be okay if they disabled my account, really. But it's not okay that I can't login but my account is active, everyone thinks I'm still there and that I don't respond on purpose or something.

Can anyone help me? If I can't get back into my account, can't it at least be disabled?