|"this computer only" was not set on the original computer|
See, when you create a rule in Outlook, a hidden value in the rule is the computer that the rule was created on, EVEN IF you don't check the option "On this computer only." (That option is more for managing rules in Microsoft Exchange.) This means that even though rules are stored in PST files, if you move a PST to a different computer Outlook will still ignore all your rules and display "(For other computer)" next to them.
One solution is to go rule by rule on the new computer and edit every one... tediously un-checking the new line item "On this computer only." THIS DOESN'T ALWAYS WORK and it's certainly not the ideal way to handle moving rules. Also, if you have a lot of rules, then this may drive you mad.
The better option is to export your rules from the original computer they were created on. This won't tie them to any computer, and allows you to import and use them wherever you want.
First, you'll have to export the rules from the original computer your Outlook was on.
To do this, open Rules...
...then the rule Options.
From here you can both Export and Import rules to a *.rwz file.
- Importing rules will not overwrite existing rules.
So, you'll have to delete duplicates manually.
- The .rwz file doesn't exist on your hard drive until you export it manually from the Rule Options
This means that there isn't an automatic way to back up your rules. If you want to keep a backup, you'll have to manually export them every time you change anything.
Bonus Fun Fact: You can select multiple rules at once in Outlook by clicking and dragging to highlight since CTRL or SHIFT clicking doesn't work.