In large scale Exchange implementations it is common for the public folder structure to become quite complex. I learned a valuable lesson yesterday with regards to public folder referrals.
When there are multiple public folder stores all part of the same hierarchy each store will have certain folders within the hierarchy that it owns. When a client accesses that folder while connected to a different public folder store there is a referral that occurs so the client can still access the information. This is called public folder referral.
In order for the referral process to work the store process (store.exe) builds a list of all folder items and the other public folder store it will refer to for each.
The lesson I learned is that the only way to rebuild the list of referral partners is to restart the store process, which will also unmount ALL the database stores on that server.