The top level rule conditions are:
- Sender is/has
- Recipient is/has
- The subject or body is/has
- Any attachment is/has
- Any recipient is/has
- The message is/has
- The sender and the recipient are/have
- The message properties are/have
- A message header is/has
For each of these, there are a group of conditions. They're different for each top-level condition; sender includes is a member of this group, is external/internal, address includes any of these words, domain is, and so forth, while the subject or body's conditions include any of these words, matches these text patterns, and so on.
Set your conditions. Remember that because there are only and operators, every condition you set will be applied in this rule. So if you say sender ...
