Read about Outlook personal folders in the hits of

There's a personal folder backup tool also, but I've excluded hits about that to keep the picture clear. It really depends on the way her data is backed up if that is relevant at all.

Note the 2Gb max file size of Outlook pst-files as discussed in If they grow above that, they might very well become corrupted and unusable. That's one of the best arguments for splitting!

Hope this helps.