This is log from dovecot 2.1.17 (I had to downgrade from 2.2.10 because lot of problems) on CentOS 6.5:

2014-01-14T18:36:03+01:00 server/a.b.c.d dovecot: lmtp(5927): Fatal: master: service(lmtp): child 5927 killed with signal 11 (core dumped)

# uname -a Linux server 2.6.32-431.1.2.0.1.el6.x86_64 #1 SMP Fri Dec 13 13:06:13 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

(gdb) bt full #0 0x00007fb14b9b3bb5 in mail_cache_header_fields_read () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #1 0x00007fb14b9b19aa in mail_cache_open_and_verify () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #2 0x00007fb14b9b35bd in mail_cache_register_get_list () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #3 0x00007fb14b9a11a7 in index_mail_parse_header_init () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #4 0x00007fb14b9a1ff8 in index_mail_cache_parse_init () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #5 0x00007fb14b94c982 in maildir_save_add () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #6 0x00007fb14b94ccd8 in maildir_save_begin () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #7 0x00007fb14b031b23 in quota_save_begin () from /usr/local/dovecot/lib/dovecot/lib10_quota_plugin.so ---Type <return> to continue, or q <return> to quit--- No symbol table info available. #8 0x00007fb14b982552 in mailbox_save_begin () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #9 0x00007fb14b97ae8f in mail_storage_copy () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #10 0x00007fb14b948ef6 in maildir_copy () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #11 0x00007fb14ae25551 in notify_copy () from /usr/local/dovecot/lib/dovecot/lib15_notify_plugin.so No symbol table info available. #12 0x00007fb14b031907 in quota_copy () from /usr/local/dovecot/lib/dovecot/lib10_quota_plugin.so No symbol table info available. #13 0x00007fb14b9824aa in mailbox_copy () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-storage.so.0 No symbol table info available. #14 0x00007fb14a9d7dc6 in act_store_execute () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-sieve.so.0 No symbol table info available. #15 0x00007fb14a9ce0f4 in _sieve_result_implicit_keep () ---Type <return> to continue, or q <return> to quit--- from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-sieve.so.0 No symbol table info available. #16 0x00007fb14a9cfe27 in sieve_result_execute () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-sieve.so.0 No symbol table info available. #17 0x00007fb14a9df918 in sieve_multiscript_run () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-sieve.so.0 No symbol table info available. #18 0x00007fb14ac2189e in lda_sieve_deliver_mail () from /usr/local/dovecot/lib/dovecot/lib90_sieve_plugin.so No symbol table info available. #19 0x00007fb14bc1d305 in mail_deliver () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot-lda.so.0 No symbol table info available. #20 0x00000000004054c3 in client_input_data_handle () No symbol table info available. #21 0x00007fb14b6ba146 in io_loop_call_io () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot.so.0 No symbol table info available. #22 0x00007fb14b6bb46d in io_loop_handler_run () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot.so.0 No symbol table info available. #23 0x00007fb14b6ba0e8 in io_loop_run () ---Type <return> to continue, or q <return> to quit--- from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot.so.0 No symbol table info available. #24 0x00007fb14b6a4043 in master_service_run () from /usr/local/dovecot-2.1.17/lib/dovecot/libdovecot.so.0 No symbol table info available. #25 0x0000000000404096 in main () No symbol table info available. (gdb)

MU