Hi, I routinely use thunderbird to access mail on a cyrus IMAP server with very large folders (thousands of archived messages).
IMAP support in the 3.1 series seems quite stable to me (whereas 2.x had frequent problems with folder indexes and 3.0.x tended to hang randomly while performing server operations) The only problem I can think of is that if you have used the default settings for the message search feature, thunderbird will attempt to build a full-text search index by downloading every message on the server (body included) when it is first run. Thunderbird will try downloading messages from multiple folders in parallel, which might cause a hign load on the server resulting in substantial delays when listing folder contents. If thunderbird is indexing messages (look at the progress indicator on the status bar), try leaving it alone until it is done -- it's a one-time process. If, on the other hand, everything is idle, I'm sorry but I have no idea. HTH, andrea
