[Evolution] imap+ still downloading a lot

[Ross Boylan <ross biostat ucsf edu>]

I've been using IMAP+ in evo 3.4.4 on Debian.  I have one very large
folder, approaching 24k messages.  Every few minutes evo shows "checking
for new messages in <folder>" and I can see my network connection
saturate (300 kiB/s) for ~ 30 seconds, during which evo is pretty
unresponsive.  The traffic drops back to around 0 once the poll is done.

When I move a message from one folder to another evo frequently (maybe
always) seems to poll both the source and destination folders.

Since IMAP was supposed to avoid constant checking of old messages, and
I thought the IMAP+ in evo took advantage of that, this behavior
surprised me.

Is there anything I can do about it?  Should I just disable the polling?

Receiving options enabled include check for new messages every 5
minutes, check for new messages in subscribed folders, use quick resync
if server supports it, and listen for server change notifications.  The
connection is over SSL.

The server is running courier 4.1.1.20060828-5 on a very old Debian.

Thanks.
Ross Boylan