It's easy to reproduce, as it happens every time ... ;-) I snipped away all communication with the second server to make it more readable. At the time of the crash, m-n was logged out of the second server (which doesn't support IDLE) and waiting for the next time to check it (every 5 minutes), if that's important. Here we go: [zlatko@disclosure]:~/usrlocal/src/mail-notification-5.4$ gdb --args ./build/src/mail-notification -i GNU gdb 6.6 Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i486-slackware-linux"... Using host libthread_db library "/lib/libthread_db.so.1". (gdb) run Starting program: /usr/local/src/mail-notification-5.4/build/src/mail-notification -i [Thread debugging using libthread_db enabled] ** INFO: ZlatkO @ Home: resolving my.imap.server ** INFO: ZlatkO @ Home: connecting to my.imap.server (192.168.1.3) port 143 ** INFO: ZlatkO @ Home: connected successfully ** INFO: ZlatkO @ Home: < * OK [CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=1 STARTTLS LOGINDISABLED AUTH=DIGEST-MD5 AUTH=CRAM-MD5] Dovecot ready. ** INFO: ZlatkO @ Home: > a000 STARTTLS ** INFO: ZlatkO @ Home: < a000 OK Begin TLS negotiation now. 13 Jul 2008 17:39:18 +0200 (CEST) ** INFO: ZlatkO @ Home: a SSL/TLS layer is now active (TLSv1, DHE-RSA-AES256-SHA 256-bit) ** INFO: ZlatkO @ Home: > a001 CAPABILITY ** INFO: ZlatkO @ Home: < * CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=1 AUTH=PLAIN AUTH=DIGEST-MD5 AUTH=CRAM-MD5 ** INFO: ZlatkO @ Home: < a001 OK Capability completed. ** INFO: ZlatkO @ Home: > a002 AUTHENTICATE CRAM-MD5 ** INFO: ZlatkO @ Home: < [ authentication snipped ] ** INFO: ZlatkO @ Home: > [ authentication snipped ] ** INFO: ZlatkO @ Home: < a002 OK Logged in. ** INFO: ZlatkO @ Home: > a003 CAPABILITY ** INFO: ZlatkO @ Home: < * CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS UIDPLUS LIST-EXTENDED I18NLEVEL=1 ** INFO: ZlatkO @ Home: < a003 OK Capability completed. ** INFO: ZlatkO @ Home: > a004 EXAMINE "INBOX" ** INFO: ZlatkO @ Home: < * FLAGS (\Answered \Flagged \Deleted \Seen \Draft NonJunk $Label1 Junk) ** INFO: ZlatkO @ Home: < * OK [PERMANENTFLAGS ()] Read-only mailbox. ** INFO: ZlatkO @ Home: < * 16 EXISTS ** INFO: ZlatkO @ Home: < * 0 RECENT ** INFO: ZlatkO @ Home: < * OK [UIDVALIDITY 1215789868] UIDs valid ** INFO: ZlatkO @ Home: < * OK [UIDNEXT 961] Predicted next UID ** INFO: ZlatkO @ Home: < a004 OK [READ-ONLY] Select completed. ** INFO: ZlatkO @ Home: > a005 SEARCH UNSEEN ** INFO: ZlatkO @ Home: < * SEARCH ** INFO: ZlatkO @ Home: < a005 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a006 IDLE ** INFO: ZlatkO @ Home: < + idling ** INFO: ZlatkO @ Home: < * OK Still here ** INFO: ZlatkO @ Home: < * OK Still here ** INFO: ZlatkO @ Home: < * 17 EXISTS ** INFO: ZlatkO @ Home: > DONE ** INFO: ZlatkO @ Home: < a006 OK Idle completed. ** INFO: ZlatkO @ Home: > a007 SEARCH UNSEEN ** INFO: ZlatkO @ Home: < * SEARCH 17 ** INFO: ZlatkO @ Home: < a007 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a008 SEARCH RECENT ** INFO: ZlatkO @ Home: < * SEARCH ** INFO: ZlatkO @ Home: < a008 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a009 FETCH 17 UID ** INFO: ZlatkO @ Home: < * 17 FETCH (UID 961) ** INFO: ZlatkO @ Home: < a009 OK Fetch completed. ** INFO: ZlatkO @ Home: > a010 FETCH 17 BODY.PEEK[HEADER] ** INFO: ZlatkO @ Home: < * 17 FETCH (BODY[HEADER] {1022} ** INFO: ZlatkO @ Home: < [ snipped raw message ] ** INFO: ZlatkO @ Home: < ) ** INFO: ZlatkO @ Home: < a010 OK Fetch completed. ** INFO: ZlatkO @ Home: > a011 IDLE ** INFO: ZlatkO @ Home: < + idling ** INFO: ZlatkO @ Home: < * 17 FETCH (FLAGS (NonJunk)) ** INFO: ZlatkO @ Home: > DONE ** INFO: ZlatkO @ Home: < * 18 EXISTS ** INFO: ZlatkO @ Home: < a011 OK Idle completed. ** INFO: ZlatkO @ Home: > a012 SEARCH UNSEEN ** INFO: ZlatkO @ Home: < * SEARCH 17 18 ** INFO: ZlatkO @ Home: < a012 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a013 SEARCH RECENT ** INFO: ZlatkO @ Home: < * SEARCH ** INFO: ZlatkO @ Home: < a013 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a014 FETCH 17,18 UID ** INFO: ZlatkO @ Home: < * 17 FETCH (UID 961) ** INFO: ZlatkO @ Home: < * 18 FETCH (UID 962) ** INFO: ZlatkO @ Home: < a014 OK Fetch completed. ** INFO: ZlatkO @ Home: > a015 FETCH 18 BODY.PEEK[HEADER] ** INFO: ZlatkO @ Home: < * 18 FETCH (BODY[HEADER] {2156} ** INFO: ZlatkO @ Home: < [ snipped raw message ] ** INFO: ZlatkO @ Home: < ) ** INFO: ZlatkO @ Home: < a015 OK Fetch completed. ** INFO: ZlatkO @ Home: > a016 IDLE ** INFO: ZlatkO @ Home: < + idling ** INFO: ZlatkO @ Home: < * 18 FETCH (FLAGS (NonJunk)) ** INFO: ZlatkO @ Home: > DONE ** INFO: ZlatkO @ Home: < a016 OK Idle completed. ** INFO: ZlatkO @ Home: > a017 SEARCH UNSEEN ** INFO: ZlatkO @ Home: < * SEARCH 17 18 ** INFO: ZlatkO @ Home: < a017 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a018 SEARCH RECENT ** INFO: ZlatkO @ Home: < * SEARCH ** INFO: ZlatkO @ Home: < a018 OK Search completed (0.000 secs). ** INFO: ZlatkO @ Home: > a019 FETCH 17,18 UID ** INFO: ZlatkO @ Home: < * 17 FETCH (UID 961) ** INFO: ZlatkO @ Home: < * 18 FETCH (UID 962) (mail-notification:6161): GLib-GObject-CRITICAL **: g_object_class_find_property: assertion `G_IS_OBJECT_CLASS (class)' failed (mail-notification:6161): GLib-GObject-CRITICAL **: g_param_spec_get_name: assertion `G_IS_PARAM_SPEC (pspec)' failed Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1240298608 (LWP 6165)] 0x08074333 in mn_g_object_clone (object=0x99a56c0, property_name=0x8097939 "flags") at src/mn-util.c:1179 1179 g_value_init(¶meter->value, G_PARAM_SPEC_VALUE_TYPE(pspec)); (gdb) bt full #0 0x08074333 in mn_g_object_clone (object=0x99a56c0, property_name=0x8097939 "flags") at src/mn-util.c:1179 pspec = (GParamSpec *) 0x0 parameter = (GParameter *) 0x9986270 error = 0x0 parameters = (GHashTable *) 0x9981cf0 args = 0xb61281d8 "" properties = (GParamSpec **) 0x997eb58 n_properties = 3075691600 i = -1219275794 parameters_array = (GArray *) 0xb61281b0 new_object = (GObject *) 0x998bfa0 #1 0x0807dd8c in mn_imap_mailbox_handle_fetch_uid_cb (session=0xb6128254, response=0x9978c40, priv=0xb61282c8) at src/mn-imap-mailbox.gob:911 message = (MNMessage *) 0x99a56c0 n = 18 info = (MessageInfo *) 0x9979258 uid = 0x99a8850 "962" #2 0x08082286 in handle_input (session=0xb6128254, input=0x9995578 "* 18 FETCH (UID 962)") at src/mn-client-session.c:320 result = -1 response = (MNClientSessionResponse *) 0x9978c40 cont = 1 #3 0x0808245c in mn_client_session_run (states=0x8097b20, callbacks=0x8097b00, use_ssl=0, server=0x997ee70 "imap.zlatko.fdns.net", port=143, private=0xb61282c8, err=0xb6128324) at src/mn-client-session.c:440 session = {states = 0x8097b20, callbacks = 0x8097b00, server = 0x997ee70 "imap.zlatko.fdns.net", port = 143, s = 20, state = 0x8097b80, error = 0x0, private = 0xb61282c8, input_buffer = 0x99126b0, bytes_to_remove = 22, ssl = 0x9994ef0, sasl_conn = 0x99a3c60, sasl_ssf = 0, sasl_maxoutbuf = 0} addrinfo = (struct addrinfo *) 0x9985a58 line = 0x9995578 "* 18 FETCH (UID 962)" #4 0x0807e7c0 in ___21_mn_imap_mailbox_authenticated_check (mailbox=0x997f060) at src/mn-imap-mailbox.gob:1284 self = (Self *) 0x997f060 priv = {mailbox = 0x997f060, auth_mailbox = 0x997f060, pi_mailbox = 0x997f060, session = 0xb6128254, self = 0x997f060, server_software = 0x0, server_software_supports_idle = 1, numeric_tag = 20, tag = "a019", capabilities = 0x99a8440, auth_mechanisms = 0x0, authenticated = 1, uidvalidity = 0x99a6d80 "1215789868", num_errors = 0, messages = 0x9981ca0, starttls_completed = 1, sasl_remaining_mechanisms = 0x0, sasl_mechanism = 0xb59232a8 "CRAM-MD5", idle_state = IDLE_STATE_POST_IDLE, idle_inactivity_timeout_id = 0, idle_inactivity = 0, could_idle = 1} status = 0 err = (GError *) 0x0 states = {{id = 1, enter_cb = 0, handle_cb = 0x807cc25 }, {id = 2, enter_cb = 0x807cd83 , handle_cb = 0x807cd9e }, {id = 3, enter_cb = 0x807cee7 , handle_cb = 0x807cf02 }, {id = 4, enter_cb = 0x807cffa , handle_cb = 0x807d098 }, { id = 5, enter_cb = 0x807d1ff , handle_cb = 0x807d2f9 }, {id = 6, enter_cb = 0x807d404 , handle_cb = 0x807d470 }, {id = 7, enter_cb = 0x807d613 , handle_cb = 0x807d678 }, { id = 8, enter_cb = 0x807d856 , handle_cb = 0x807d871 }, {id = 9, enter_cb = 0x807da53 , handle_cb = 0x807dbe1 }, {id = 10, enter_cb = 0x807ddc8 , handle_cb = 0x807de99 }, {id = 11, enter_cb = 0x807e196 , handle_cb = 0x807e2dd }, {id = 12, enter_cb = 0x807e619 , handle_cb = 0x807e634 }, {id = 0, enter_cb = 0, handle_cb = 0}} callbacks = {notice = 0x80811c1 , warning = 0x80811e2 , response_new = 0x807e901 , response_free = 0x807eb1d , pre_read = 0x807ebe4 , post_read = 0x807ec4b , ---Type to continue, or q to quit--- sasl_get_credentials = 0x8080e6a , ssl_trust_server = 0x8080ed4 } #5 0x080848bb in mn_authenticated_mailbox_authenticated_check (self=0x997f060) at mn-authenticated-mailbox.c:644 klass = (MNAuthenticatedMailboxClass *) 0x997e478 #6 0x08084850 in mn_authenticated_mailbox_check_thread_cb (self=0x997f060) at src/mn-authenticated-mailbox.gob:227 No locals. #7 0xb7569aab in g_thread_create_proxy () from /usr/local/lib/libglib-2.0.so.0 No symbol table info available. #8 0xb72d91b3 in start_thread () from /lib/libpthread.so.0 No symbol table info available. #9 0xb726203e in clone () from /lib/libc.so.6 No symbol table info available. (gdb)