Please find Backtrace for LMTP Core Dump below:

[...] ==> /var/log/dovecot/dovecot.log <== Nov 1 11:16:14 spectre dovecot: lmtp(17245): Connect from local Nov 1 11:16:14 spectre dovecot: lmtp(17245): Fatal: master: service(lmtp): child 17245 killed with signal 11 (core dumped)

==> /var/log/mail.log <== Nov 1 11:16:14 spectre postfix/lmtp[17204]: 3Xsj4G11MrzNY: to=<tlx@leuxner.net>, relay=spectre.leuxner.net[private/dovecot-lmtp], delay=0.11, delays=0.06/0/0.01/0.04, dsn=4.4.2, status=deferred (lost connection with spectre.leuxner.net[private/dovecot-lmtp] while sending MAIL FROM) [...]

$ gdb /usr/lib/dovecot/lmtp /tmp/core

Program terminated with signal 11, Segmentation fault. #0 0x00007f6174db3d35 in mail_storage_service_lookup (ctx=0x1160640, input=0x7fff905265d0, user_r=<value optimized out>, error_r=<value optimized out>) at mail-storage-service.c:1013 1013 mail-storage-service.c: No such file or directory. in mail-storage-service.c (gdb) bt full #0 0x00007f6174db3d35 in mail_storage_service_lookup (ctx=0x1160640, input=0x7fff905265d0, user_r=<value optimized out>, error_r=<value optimized out>) at mail-storage-service.c:1013 flags = 675 user = <value optimized out> username = 0x11540b0 "tlx@leuxner.net" user_info = 0x1163718 user_set = <value optimized out> userdb_fields = 0x1173dd8 error = <value optimized out> reply = {uid = 0, gid = 0, home = 0x7f6175249712 "H\211\303d\213\004%\030", chroot = 0x7f6100000001 <Address 0x7f6100000001 out of bounds>, extra_fields = {arr = {buffer = 0x0, element_size = 18170192}, v = 0x0, v_modifiable = 0x0}, anonymous = 0} set_parser = 0x1167500 sets = 0x0 user_pool = 0x11705e0 temp_pool = 0x1173db0 ret = 1 #1 0x0000000000406c16 in cmd_rcpt (client=0x1161e70, args=0x116d623 "") at commands.c:545 rcpt = {address = 0x0, detail = 0x0, service_user = 0x0} input = {module = 0x40823a "lmtp", service = 0x40823a "lmtp", username = 0x11540b0 "tlx@leuxner.net", session_id = 0x0, local_ip = {family = 0, u = {ip6 = {__in6_u = { __u6_addr8 = '\000' <repeats 15 times>, __u6_addr16 = {0, 0, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {0, 0, 0, 0}}}, ip4 = {s_addr = 0}}}, remote_ip = {family = 0, u = {ip6 = {__in6_u = { __u6_addr8 = '\000' <repeats 15 times>, __u6_addr16 = {0, 0, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {0, 0, 0, 0}}}, ip4 = {s_addr = 0}}}, local_port = 0, remote_port = 0, userdb_fields = 0x0, flags_override_add = 0, flags_override_remove = 0, no_userdb_lookup = 0} address = 0x11540b0 "tlx@leuxner.net" username = 0x11540b0 "tlx@leuxner.net" detail = 0x4086a3 "" error = 0x0 ret = <value optimized out> #2 0x00000000004055fb in client_input_line (client=0x1161e70) at client.c:60 cmd = <value optimized out> args = 0x116d60f "TO:<tlx@leuxner.net>" #3 client_input_handle (client=0x1161e70) at client.c:113 _data_stack_cur_id = 3 output = 0x11610e8 line = <value optimized out> ret = <value optimized out> #4 0x00007f6174afd186 in io_loop_call_io (io=0x1161190) at ioloop.c:387 ioloop = 0x115c670 t_id = 2 #5 0x00007f6174afe1d7 in io_loop_handler_run (ioloop=<value optimized out>) at ioloop-epoll.c:215 ctx = 0x115f4a0 event = 0x115f510 list = 0x11611e0 io = 0x11540b0 tv = {tv_sec = 299, tv_usec = 999016} msecs = <value optimized out> ret = 1 i = 0 call = false #6 0x00007f6174afd128 in io_loop_run (ioloop=0x115c670) at ioloop.c:406 No locals. #7 0x00007f6174ae6473 in master_service_run (service=0x115c510, callback=0x1173e08) at master-service.c:546 No locals. #8 0x0000000000404a06 in main (argc=1, argv=0x115c370) at main.c:122 set_roots = {0x60a8e0, 0x408e20, 0x0} service_flags = <value optimized out> storage_service_flags = 675 c = <value optimized out>

[ doveconf -n ]

# 2.2.alpha1 (626a9df21e62): /etc/dovecot/dovecot.conf # OS: Linux 2.6.32-5-amd64 x86_64 Debian 6.0.6 auth_cache_size = 16 k auth_verbose = yes mail_location = mdbox:~/mdbox mail_plugins = acl quota stats namespace { list = yes location = mdbox:/var/vmail/public prefix = Public/ separator = / subscriptions = no type = public } namespace inbox { hidden = no inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Trash { special_use = \Trash } prefix = separator = / type = private } passdb { args = username_format=%u /var/vmail/auth.d/%d/passwd driver = passwd-file } plugin { acl = vfile:/var/vmail/conf.d/%d/acls:cache_secs=300 mail_log_events = expunge mailbox_delete quota = dict:user::file:%h/mdbox/dovecot-quota quota_rule = *:storage=1GB quota_rule2 = Trash:storage=+10%% sieve = ~/.dovecot.sieve sieve_dir = ~/sieve sieve_global_dir = /var/vmail/conf.d/%d/sieve stats_refresh = 30s stats_track_cmds = yes } protocols = " imap lmtp" quota_full_tempfail = yes service auth-worker { unix_listener auth-worker { user = doveauth } user = doveauth } service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } user = doveauth } service imap-login { inet_listener imap { address = 1.2.3.4 port = 143 } inet_listener imaps { port = 0 } } service lmtp { unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0660 user = postfix } } service stats { fifo_listener stats-mail { mode = 0600 user = vmail } } ssl_ca = </etc/ssl/certs/SSL123_CA_Bundle.pem ssl_cert = </etc/ssl/certs/host_domain_tld.crt ssl_key = </etc/ssl/private/host_domain_tld.key syslog_facility = local1 userdb { args = username_format=%u /var/vmail/auth.d/%d/passwd driver = passwd-file } verbose_proctitle = yes protocol lmtp { mail_plugins = acl quota stats sieve } protocol imap { mail_max_userip_connections = 20 mail_plugins = acl quota stats imap_acl imap_quota mail_log notify imap_stats }