Emails to Hotmail bouncing

550 Command rejected for policy reasons

[jecasc]

A few days ago the emails sent from my shopping cart to customers with Hotmail accounts began to bounce.

Always the same message:
550 Command rejected for policy reasons

However I can't figure out the reason. First I thought there was a problem with the SPF record but everything is ok.

Besides I have not made any changes recently. So Hotmail must have changed something in the last few days. Does anybody have information about recent changes?

[jecasc]

OK - problem not solved but at least I know what the problem is. I contacted the support of my webhosting company and it seems that the server is currently blacklisted by msn. So I think it is time to move on to a dedicated server. A pity since the virtual server I had now was more than sufficent. But probably having an own IP adress is worth paying 60EUR/month more.

I only wish MSN could use an error code that is a little more specific. Like "Your server has been blacklisted, contact your Webhosting company."