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?

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

Answer 1

Here's a helpful answer.

"...The technology used for message content analysis is also far from being perfect. Microsoft has created a dictionary of several tens thousand words, and assigned different weights to the words in the dictionary. The message content analysis is nothing more than mere summation of weights of words contained in the message."

And here's another one.

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But bear in mind:

• Microsoft intentionally keeps Outlook's spam filtering rules secret.
• Because if they didn't, spammers would have a playbook for which they could circumvent the rules.