can the ci files be deleted safely from Exchange 2007? should I keep the latest one? seems to me the older the file the bigger it is?

a bit suprising....

As I know, you can only rebuild the index files but not remove a part of the files How to Rebuild the Full-Text Index Catalog When the number and size of the CI files grow too large, a Master Merge is performed automatically by design to consolidate the indexes and shrink the overall size of the Content Index During a Master Merge of the Content Index files, the “Catalog” folder containing the content index files typically grow twice the normal size or up to 20% of the mailbox database size. You may see the “Catalog” folder grow larger than 20% - from 50% to 167% of the mailbox database size during the procedurePlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

If you want to manually clear the CI files for some reason: Log in to the Exchange server and stop Microsoft Search (Exchange) and Microsoft Exchange Search Indexer services. Delete CI files (you may delete everything in the folder). Start Microsoft Search (Exchange) and Microsoft Exchange Search Indexer services, verify that new files are created. May take more than 30 minutes. If CI files are not created, then Mount/Dismount the corresponding database and/or restart Store.exe We have seen that the Exchange server Processor/Memory utilization go up while the indexes are being re-created.- Thanks, Jinesh.