[Evolution] problem with imap

[Gregor Welters <entwicklung weos de>]

Since I'm using a new imap-server I get perpetually errors after a few
minutes runtime of evolution 1.2.4 (I translate the messages from
german):

"Error while ping to IMAP-server xxx is aquired: Connection to server
unexpectedly lost: Connection reset by host"

after that, when trying to open a folder or email:

"Error when accessing Message xx: file or folder not found"

My server-admin says, that comes because evolution isn't correctly
shutting down it's imap-connections so it opens really a lot of them and
he had to set some limits to prevent the server from crashing or being
overburdened. He uses mulberry and has absolutely no problem...

We are using cyrus, but our last server used some other program and I
had the same problems. 

Question is:
Is it a bug or a configuration problem?

Any help would really be appreciated!

Gregor