Hi Forum, it took us some time but now we have investigated the cause of IMAP Clients not being able to subscribe all folders of a certain mailbox: Exchange 2007 seems to accept a list of subscribed folders not larger than 16 Kilobytes... Does anyone know if this limit can be pushed up? Details: What the clients see is that it is not possible to subscribe all folders of a certain mailbox with *a lot* of subfolders. It doesn't matter if people are using Outlook with IMAP or Thunderbird with IMAP. It is NOT the number of folders subscribed that sets the limit, but the size of the list containing the names of the folders: as a user unsubscribes one folder with 8 characters he can subscribe two folders with 4 characters each. Using a script to check via IMAP which folders are subscribed gives out a list of exactly 16KB in size. This limit did not exist with Exchange 2003, our clients did not have any problems. Also Sync of this "IMAP mailbox" is very slow, but this might be another problem and is just mentioned for the case it does depend anyhow. Due to legacy reasons we have to use this one mailbox with IMAP - not MAPI. Also the number / leght of names of folders can't be reduced. So we are in kind of trouble here... Did anybody of you experience the same problem? Is there a workaround? Thanks for your thoughts, Thomas

Hi, What error message you got when trying to subscript the folders?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Thanks Gen Lin-MSFT