From the log:

Jan 7 20:03:11 postamt dovecot: imap-login: Login: user=<hxxxxl>, method=PLAIN, rip=10.47.32.220, lip=141.42.206.36, mpid=2176, TLS Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Disconnected: Disconnected in IDLE bytes=8855/771339 Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Panic: Message count decreased Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Error: Raw backtrace: /usr/dovecot-2/lib/dovecot/libdovecot.so.0(+0x3b861) [0xb75ff861] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(+0x3b8cf) [0xb75ff8cf] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(i_fatal+0) [0xb75d669e] -> dovecot/imap hxxxxl 10.47.32.188 IDL E [0x805ed4f] -> dovecot/imap hxxxxl 10.47.32.188 IDLE [0x805119a] -> dovecot/imap hxxxxl 10.47.32.188 IDLE [0x8051450] -> dovecot/imap hxxxxl 10.47.32.188 IDLE [0x8056924] -> dovecot/imap hxxxxl 10.47.32.188 IDLE [0x80572cb] -> dovecot/imap hxxxxl 10.47.32.188 IDLE [0x805157a] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x51) [0xb760cd81] -> /usr/dovecot-2/lib/dovecot/libdovecot.so .0(io_loop_handler_run+0xd3) [0xb760dfb3] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0xb760cd00] -> /usr/dovecot-2/lib/dovecot/libdovec ot.so.0(master_service_run+0x2a) [0xb75f88ea] -> dovecot/imap [hxxxxl 10.47.32.188 I Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Error: FETCH [] for mailbox INBOX.Alte Mails.2010 UID 1980 got too little data: 69693 vs 204062 Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Error: Maildir filename has wrong W value: /home/h/u/hxxxxl/Maildir/.Alte Mails.2010/cur/1268820413.M565982P24 483.postamt.charite.de,S=201188,W=204062:2,SZ Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Error: Corrupted index cache file /home/h/u/hxxxxl/Maildir/.Alte Mails.2010/dovecot.index.cache: Broken virtua l size for mail UID 1980 Jan 7 20:03:11 postamt dovecot: imap(hxxxxl): Disconnected: FETCH failed bytes=149/70670 Jan 7 20:03:11 postamt dovecot: master: Error: service(imap): child 3387 killed with signal 6 (core dumped)

GNU gdb (GDB) 7.0.1-debian Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "i486-linux-gnu". For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>... Reading symbols from /usr/dovecot-2/libexec/dovecot/imap...done. Reading symbols from /usr/dovecot-2/lib/dovecot/libdovecot-storage.so.0...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/libdovecot-storage.so.0 Reading symbols from /usr/dovecot-2/lib/dovecot/libdovecot.so.0...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/libdovecot.so.0 Reading symbols from /lib/i686/cmov/libc.so.6...Reading symbols from /usr/lib/debug/lib/i686/cmov/libc-2.11.2.so...done. (no debugging symbols found)...done. Loaded symbols for /lib/i686/cmov/libc.so.6 Reading symbols from /lib/i686/cmov/libdl.so.2...Reading symbols from /usr/lib/debug/lib/i686/cmov/libdl-2.11.2.so...done. (no debugging symbols found)...done. Loaded symbols for /lib/i686/cmov/libdl.so.2 Reading symbols from /lib/i686/cmov/librt.so.1...Reading symbols from /usr/lib/debug/lib/i686/cmov/librt-2.11.2.so...done. (no debugging symbols found)...done. Loaded symbols for /lib/i686/cmov/librt.so.1 Reading symbols from /lib/ld-linux.so.2...Reading symbols from /usr/lib/debug/lib/ld-2.11.2.so...done. (no debugging symbols found)...done. Loaded symbols for /lib/ld-linux.so.2 Reading symbols from /lib/i686/cmov/libpthread.so.0...Reading symbols from /usr/lib/debug/lib/i686/cmov/libpthread-2.11.2.so...done. (no debugging symbols found)...done. Loaded symbols for /lib/i686/cmov/libpthread.so.0 Reading symbols from /usr/dovecot-2/lib/dovecot/lib10_quota_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib10_quota_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib11_imap_quota_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib11_imap_quota_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib11_trash_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib11_trash_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib15_notify_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib15_notify_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib20_fts_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib20_fts_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib20_mail_log_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib20_mail_log_plugin.so Reading symbols from /usr/dovecot-2/lib/dovecot/lib20_zlib_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib20_zlib_plugin.so Reading symbols from /usr/lib/libz.so.1...(no debugging symbols found)...done. Loaded symbols for /usr/lib/libz.so.1 Reading symbols from /lib/libbz2.so.1.0...(no debugging symbols found)...done. Loaded symbols for /lib/libbz2.so.1.0 Reading symbols from /usr/dovecot-2/lib/dovecot/lib21_fts_squat_plugin.so...done. Loaded symbols for /usr/dovecot-2/lib/dovecot/lib21_fts_squat_plugin.so Reading symbols from /lib/libgcc_s.so.1...(no debugging symbols found)...done. Loaded symbols for /lib/libgcc_s.so.1 Core was generated by `dovecot/imap'. Program terminated with signal 6, Aborted. #0 0xb76fa430 in __kernel_vsyscall () #0 0xb76fa430 in __kernel_vsyscall () No symbol table info available. #1 0xb749b751 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64 resultvar = <value optimized out> pid = -1218760716 selftid = 3387 #2 0xb749eb82 in *__GI_abort () at abort.c:92 act = {__sigaction_handler = {sa_handler = 0xbff2cfb0, sa_sigaction = 0xbff2cfb0}, sa_mask = {__val = {3077545392, 3220361092, 3077587362, 3220361076, 3076292096, 3220361064, 3077667412, 0, 3076226344, 1, 0, 1, 3077544952, 34, 3220360984, 3076517792, 3076512619, 3076732136, 3220361068, 150915560, 0, 3220361136, 3220361064, 3220361076, 3076517485, 3077544952, 0, 1130, 3220361096, 3076317943, 3220361068, 10}}, sa_flags = -1074606108, sa_restorer = 0xb76349cc <pid.3441>} sigs = {__val = {32, 0 <repeats 31 times>}} #3 0xb75ff875 in default_fatal_finish (type=<value optimized out>, status=<value optimized out>) at failures.c:187 backtrace = 0x8fec1d8 "/usr/dovecot-2/lib/dovecot/libdovecot.so.0(+0x3b861) [0xb75ff861] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(+0x3b8cf) [0xb75ff8cf] -> /usr/dovecot-2/lib/dovecot/libdovecot.so.0(i_fatal+0) [0xb75d6"... #4 0xb75ff8cf in i_internal_fatal_handler (ctx=0xbff2d054, format=0x80630b4 "Message count decreased", args=0xbff2d074 "\213") at failures.c:645 status = 0 #5 0xb75d669e in i_panic (format=0x80630b4 "Message count decreased") at failures.c:259 ctx = {type = LOG_TYPE_PANIC, exit_status = 0, timestamp = 0x0} args = 0xbff2d074 "\213" #6 0x0805ed4f in imap_sync_deinit (ctx=0x9038688, sync_cmd=0x9016048) at imap-sync.c:242 client = 0x9015be0 status = {messages = 267, recent = 5, unseen = 18, uidvalidity = 1164189497, uidnext = 65779, first_unseen_seq = 0, highest_modseq = 54425, virtual_size = 0, keywords = 0x0, cache_fields = 0x0, nonpermanent_modseqs = 0} sync_status = {sync_delayed_expunges = 0} ret = 0 #7 0x0805119a in idle_finish (ctx=0x90160d0, done_ok=false, free_cmd=false) at cmd-idle.c:38 client = 0x9015be0 #8 0x08051450 in cmd_idle_continue (cmd=0x9016048) at cmd-idle.c:224 client = 0x9015be0 ctx = 0x90160d0 orig_offset = 771339 #9 0x08056924 in client_command_cancel (_cmd=0xbff2d1ec) at imap-client.c:126 cmd = 0x9016048 cmd_ret = <value optimized out> #10 0x080572cb in client_destroy (client=0x9015be0, reason=<value optimized out>) at imap-client.c:190 cmd = 0x9016048 __FUNCTION__ = "client_destroy" #11 0x0805157a in idle_client_input (ctx=0x90160d0) at cmd-idle.c:103 client = 0x9015be0 #12 0xb760cd81 in io_loop_call_io (io=0x9035fe0) at ioloop.c:383 ioloop = 0x8ff4368 t_id = 2 #13 0xb760dfb3 in io_loop_handler_run (ioloop=0x8ff4368) at ioloop-epoll.c:213 ctx = 0x8ff4490 events = <value optimized out> event = 0x8ff44d0 list = 0x9015ff0 io = <value optimized out> tv = {tv_sec = 29, tv_usec = 999920} events_count = 151085040 msecs = 1 ret = 1 i = <value optimized out> j = <value optimized out> call = <value optimized out> #14 0xb760cd00 in io_loop_run (ioloop=0x8ff4368) at ioloop.c:404 No locals. #15 0xb75f88ea in master_service_run (service=0x8ff42b8, callback=0x805fc20 <client_connected>) at master-service.c:484 No locals. #16 0x08060365 in main (argc=1, argv=0x8ff41c0) at main.c:375 set_roots = {0x8062ce0, 0x0} service_flags = <value optimized out> storage_service_flags = <value optimized out> postlogin_socket_path = <value optimized out> username = <value optimized out> c = <value optimized out>

-- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebrandt@charite.de | http://www.charite.de