Main page: https://mail.live.com/mail/services.aspx
To monitor how bad your e-mails are being delivered to Hotmail/Live (and possibly other evil derivatives such as Bell Sympatico), you can request access to the "SNDS" service of Hotmail (their fancy way of calling it "postmaster tools").
Start here: https://postmaster.live.com/snds/
Then click on "request access", i.e. https://postmaster.live.com/snds/addnetwork.aspx
It will then ask you for an IP or range that you want to monitor.
If not already logged-in, it will request that you to sign in using a "passport" account, which is Microsoft's centralized login service. You can sign up using your own e-mail address.
Then start over again, enter the IP, and it will request that you confirm the request for access by sending an e-mail to a list of pre-determined addresses, such as email@example.com (where "example.org" is the reverse DNS matching the IP).
Once that is done, you can see the stats of how many e-mails were received, how many were delivered, who complained that it was spam, etc.
When users click on the "this is junk" icon of the webmail, you can get a notification to receive a copy of the message and the user who reported it.
Fill in the form
Wait for Microsoft to acknowledge...
Hotmail likes OpenSPF, which they call SenderID.
- Start here: http://www.openspf.net/
Hotmail has a wizard somewhere on their site to create an OpenSPF record for your DNS, but the OpenSPF tools are much more usable.