I am no expert, but this works for me:
First Create a contact for yourself with the SMTP address that has the spam problem.
Second Create a Folder that you want to use for the SMTP mail.
Open up the rules wizard and set up a rule to:
1. Apply this rule after the message arrives
2. Sent To: (Pick your contact that you created.)
3. Move To the (folder you created)folder.
4. Set up any exceptions you want.
5. Give it a name.
6. Finish
There is probably a dozen ways to do it, and there might even be something built in Outlook, but this works for me just fine.