Hotmail is in danger of becoming an e-mail island because from what I read elsewhere they're blocking a lot of legitimate servers from sending e-mail to them. They then make the server administrators jump through a gazillion hoops to find out why they've been blocked, and another gazillion to get off the block.
Only for you to be blocked a couple of weeks later again.
Our server has LESS than 0.1% reported spam according to the statistics from Hotmail themselves, so I fail to see why we've been blocked when their own site suggests you'd need somewhere around 30% to be blocked.
But in any case, if you're using Hotmail for your notifications, you probably won't get any. Please switch to use an alternative provider, I shall be stopping supporting Hotmail altogether because it takes up too much time to resolve.