When do I need to use Remote User Collections?
Note that a Remote User Collection (RUC) is a mail sync collection in which the "Switch mailbox and preserve offline folder (OST) files" option is selected in the collection Properties under Workflow settings.
A RUC should be used when it is vital that the user's OST file be preserved.
This can be because:
1. Users are working offline (with an OST not fully synchronized with the online mailbox).
2. Users are working in cached mode & have very large mailboxes & it will take an unacceptable time to rebuild the OSTs when first logging on to the target mailboxes.
3. Multiple users with large mailboxes will be logging on to their target mailboxes for the first time (using cached mode) around the same time, which will cause a big hit upon the target Exchange server when all their OSTs are rebuilt at the same time.
With points 2 & 3 above, only testing & piloting will provide any indication for what the impact will be in each individual customer environment. A RUC works differently to a normal sync collection. It is generally best to use normal sync collections for the large bulk of mailboxes instead of RUCs if possible. This is an important part of migration planning & as such should be discussed with Quest Professional Services during the planning phase.