Is it possible to actually unblock my little mismanaged mailserver from hotmail?

I run a little mail server that hosts about 8 accounts. One of my users had their password guessed and someone in Russia used my server to send out a bunch of spam. The server wasn't compromised and the spam stopped as soon as the user's password was changed.

Now, however, hotmail and whatever other mail services Microsoft runs are blocking my server because it is supposedly harvesting email.

Back in the day, I could've sent a note to postmaster@theplaceImhavingaproblemwith.com and an admin would've helped me out. As it is, that account for hotmail is just an autoresponder that aims you at a wealth of unhelpful web text.

There is a form at support.live.com/eformpost.aspx that seems like it could be helpful, but when submitted, there is no indication that the form submission was successful and it's been a week since the last time I submitted it so I'm thinking it's either broken or just as unmanned as the postmaster address.

So, my question is, does anyone have any experience dealing with these guys or is this ip address permanently spoiled as a mail server as far as microsoft is concerned?