My record looks fine, how come I get a TempError from Hotmail and how do I fix it?
Hotmail does not use live DNS for Sender ID. They have a DNS cache that they update twice per day. All TempError means is that your domain's SPF record is not in their cache. To get your record added to their cache, send an e-mail message to senderid@microsoft.com with your domain in it. They will add it, but be patient as it's a manual process and the cache only updates twice a day.
PTR mechanisms in your record will only match if the data needed is in their cache. While PTR has some added risk compared to other mechanisms because of the quality of reverse DNS information, PTR is particularly risky with Hotmail.