not delivered? or delivered to the junkmail folder?
emails that behave like mailing list emails are auto routed into the junk folder by default
its all anti spam measures with hotmail.
most important rules are :
the to: line needs to be to the hotmail address
conformity in the headers is a plus, dont let the headers make you look like a spammer, with multiple domains and addresses and so on.
your biggest drawback might be that your smtp server address has no reverse dns listing (i assume)
your smtp server should be attached via the ip to an existing domain, if you have a dynamic address and no domain name for your computer then you look like a spammer and could get bounced by more then just hotmail (aol, earthlink etc.)
A nice fix is go use the no-ip.com service (www.no-ip.com)
they give you a client that updates their dns servers with your current ip address and you then pick a 3rd level domain to use to access that address (ie: yourname.sytes.net)
then if you use you@yourname.sytes.net as your address, picky servers will find a legit reverse dns listing and let your mail through.