Problems with hotmail

Hi Everyone

I've just launched my new photo hosting site Simplebucket.com but have a problem with sending emails to Hotmail. From the mail log, it looks like the email was sent but the message from Hotmail was message was queued, but it was never delivered or even gone to the SPAM folder. Anyone having this problem with hotmail and managed to figure out what's wrong?

Other email services seem to work just fine.

Mar 25 11:43:55 none postfix/smtpd[1972]: connect from localhost[127.0.0.1]

Mar 25 11:43:55 none postfix/smtpd[1972]: 3653B2C43A: client=localhost[127.0.0.1]

Mar 25 11:43:55 none postfix/cleanup[1975]: 3653B2C43A: message-id=<47e91dbbcf59_6e9b2097e3dc79b@simplebucket.com.tmail>

Mar 25 11:43:55 none postfix/qmgr[29090]: 3653B2C43A: from=<noreply@simplebucket.com>, size=766, nrcpt=1 (queue active)

Mar 25 11:43:55 none postfix/smtpd[1972]: disconnect from localhost[127.0.0.1]

Mar 25 11:43:58 none postfix/smtp[1976]: 3653B2C43A: to=<xxxxx@hotmail.com>, relay=mx4.hotmail.com[65.54.244.232]:25, delay=3.6, delays=0.08/0.03/3.2/0.27, dsn=2.0.0, status=sent (250 <47e91dbbcf59_6e9b2097e3dc79b@simplebucket.com.tmail> Queued mail for delivery)

Mar 25 11:43:58 none postfix/qmgr[29090]: 3653B2C43A: removed