Advanced setup for e-mail possible?

[nephros]

To answer the original question:

1. Open Settings
2. Go to Accounts
3. Select your IMAP account
4. Scroll to the ‘Synced Folders’ selector
5. Change setting to ‘Custom’
6. Use the new ‘Folders to sync’ button to configure synced folders.

Note that some Folders are special (see above) and messing with those may do more harm than good.