[sylpheed:34291] Problems while moving messages

[Andres Buhlmann]

Hi

I'm trying to move messages (several thousand) from one IMAP account to
another one. But the process stops regularly after about 200-400
messages. The debug output tells me the following:

[18:04:44] IMAP4> 414 APPEND UPF (\Seen) "13-Jun-2008 13:53:16 +0200" {3033}
[18:04:44] IMAP4< + Ready to read 3033 octets.
[18:04:44] IMAP4> (sending file...)
[18:04:45] IMAP4< 414 NO Mailbox cannot be locked - is there another session active?

However, I'm pretty sure that there is no other session active. There
is also no automatic mail checking in the background.
I have recompiled with threads disabled, but still no success.

Does anybody have an idea what's going on? I'm on 3.1.0beta3.
Thanks
Andres