How does Outlook 2007 decide if it should redirect an e-mail to the Junk E-mail folder?

Question

My Question:

How does Outlook 2007 decide if it should redirect an e-mail to the Junk E-mail folder?

Background Story: When I send a simple HTML e-mail from my domain mailbox, it's being redirected to the Junk E-mail folder.

Here are two sub questions:

1. Does Outlook 2007 care if the sender's outbound mailbox's reverse PTR is incorrectly configured? [If so, how can it check?]
2. Does Outlook 2007 care if the sender doesn't provide a plain text version of the HTML content?

It turns out, I'm not the only one wondering about Outlook's junk algorithm. See the comments attached to this answer.

Answer 1

To answer your first question, see this Microsoft page: Overview of the Junk E-mail Filter.

Answer 2

Here's a helpful answer.