Unlisted add-ons have Full or Preliminary approval levels, as explained here. However, an upcoming change will make that distinction pointless, after which all unlisted add-ons will get Full Review.

Post-review

All unlisted submissions are automatically approved. Our role is to go over the list of pre-approved add-ons and verify they are safe.

The review process works as follows:

1. Go to the All Unlisted Add-ons list.
2. Pick an add-on to review. They should be prioritized by two factors: whether they have been reviewed before (see the Last Review column), and the percentage of sideloaded installs (preliminary data).
3. Review the add-on.
4. If there are no problems with the add-on, add a Comment indicating it's okay. This will update the Last Review column, telling other reviewers to pick something else. If there are problems, file a blocklist bug or contact the amo-admins team. An Info Request can be sent if there are questions for the developer. The other resolutions aren't useful in this context.

What to look for

• Potentially malicious code or serious security problems.
• Remote code may be okay for content (coupon extensions) but definitely not for chrome (unless it's an iframe with type=content).
• CSP manipulation on sites like Facebook or online banking.
• Content policies don't apply to Unlisted add-ons. Adult material, gambling, copyrighted media downloads, etc. are not prohibited. There are also many unlisted add-ons that are forks or very close copies of other add-ons. They are allowed as well.