This is something I've been meaning to get to the bottom of for years.
We have an extensive shared mail folder system, probably about 2,000+ nested directories.
When connecting with particular mobile IMAP clients (in this case the stock Android mail application and also K-9 mail) they seem to list all directories in the folder list rather than showing them in a hierarchy where you can expand to view the sub-directories. This means that when trying to navigate to a folder at the bottom of an alphabetical list (e.g. Trash or Sent) you have to scroll down past hundreds of other mail directories.
Is this something that is handled by the IMAP client or is there a way to override this behaviour in Zimbra's IMAP server? Like a way of only returning the currnt level of directories when an IMAP folder list command is received?
I don't know enough detail of the IMAP specifications to know how it operates or if this is possible or not.