Sorry, this time I've no core file, (I forgot to set ulimit -c unlimited before starting dovecot)
Regards, Diego.
dovecot: Dec 09 08:26:52 Panic: IMAP(user): file mbox-sync-rewrite.c: line 590 (mbox_sync_rewrite): assertion failed: (mails[idx].from_offset == start_offset) dovecot: Dec 09 08:26:52 Error: IMAP(user): Raw backtrace: /usr/libexec/dovecot/imap [0x80f739e] -> /usr/libexec/dovecot/imap [0x80f7c5f] -> /usr/libexec/dovecot/imap(i_fatal+0) [0x80f7518] -> /usr/libexec/dovecot/imap(mbox_sync_rewrite+0x6e8) [0x8094e45] -> /usr/libexec/dovecot/imap [0x809105c] -> /usr/libexec/dovecot/imap [0x8091d77] -> /usr/libexec/dovecot/imap [0x809277e] -> /usr/libexec/dovecot/imap(mbox_sync+0x2b) [0x8092a0a] -> /usr/libexec/dovecot/imap [0x8084ff3] -> /usr/libexec/dovecot/imap(mailbox_close+0x47) [0x80b701c] -> /usr/libexec/dovecot/imap(cmd_close+0xc0) [0x805b5d8] -> /usr/libexec/dovecot/imap [0x80625c4] -> /usr/libexec/dovecot/imap [0x80627f9] -> /usr/libexec/dovecot/imap [0x80628f7] -> /usr/libexec/dovecot/imap [0x8062933] -> /usr/libexec/dovecot/imap(client_input+0xb7) [0x8062ac1] -> /usr/libexec/dovecot/imap(io_loop_handler_run+0x17d) [0x8101ecd] -> /usr/libexec/dovecot/imap(io_loop_run+0x35) [0x8101164] -> /usr/libexec/dovecot/imap(main+0xb0) [0x806df19] -> /lib/libc.so.6(__libc_start_main+0xdc) [0x7a5dec] -> /usr/libexec/dovecot/imap [0x805a2b1]