I want to know why? I have SPF, reverse DNS, everything - yet anything I sent to Yahoo! (and I don't know what else) automatically gets stuck in the bulk mail folder. Here's the strangest of all, though - if I send it through PHP, it goes through just fine. However, if I sent it via Outlook, which uses the actual SMTP mail server (a different server from the one it's hosted on), the mail gets read as bulk. I would think it would be the other way around!
Any ideas? If you want to check for yourself, you can run dnstools on come2store.com