Most forums do not have that kind of longevity. Forums are normally trimmed of old posts at regular intervals. It would be unlikely that forum software would come with that kind of detail in the search. It may be possible to custom program the feature, but it would be lost when the software is updated. I've been trying to update this forum software for awhile now, but the posts will not convert properly and 75% of them are not available after conversion. Once I am able to upgrade the software I will have a look at the search feature in the new version and see if filters can be added.