I do always get a panic on service lmtp, while receiving a mail by postfix through always_bcc, containing an attachment. If the bcc recipient would be supplied by a small delay, I would say that the panic wouldn't occur, but I don't know how to verify this. dovecot is configured with 'mail_attachment_dir' and the public namespace location is sdbox
dovecot log: Aug 6 14:18:02 dovecot dovecot: lmtp(20367, vscanner@fischer-ing.de): Panic: file fs-api.c: line 615 (fs_copy): assertion failed: (src->fs == dest->fs) Aug 6 14:18:02 dovecot dovecot: lmtp(20367, vscanner@fischer-ing.de): Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(+0x66676) [0x443676] -> /usr/lib/dovecot/libdovecot.so.0(+0x66700) [0x443700] -> /usr/lib/dovecot/libdovecot.so.0(+0x18c23) [0x3f5c23] -> /usr/lib/dovecot/libdovecot.so.0(+0x2278b) [0x3ff78b] -> /usr/lib/dovecot/libdovecot-storage.so.0(sdbox_copy+0x4ad) [0x23c6ad] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_copy+0x62) [0x27da72] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_save_using_mail+0x2b) [0x27db4b] -> /usr/lib/dovecot/libdovecot-lda.so.0(mail_deliver_save+0x1a1) [0x5dd3c1] -> /usr/lib/dovecot/libdovecot-lda.so.0(mail_deliver+0x143) [0x5dd7c3] -> dovecot/lmtp() [0x804d090] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x43) [0x455973] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0xdb) [0x456c4b] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x48) [0x4558b8] -> /usr/lib/dovecot/libdovecot.so.0(master_service_run+0x2e) [0x3fb0ee] -> dovecot/lmtp(main+0x1b3) [0x804b463] -> /lib/libc.so.6(__libc_start_main+0xe6) [0x5f9d26] -> dovecot/lmtp() [0x804b1e1] Aug 6 14:18:02 dovecot dovecot: lmtp(20367, vscanner@fischer-ing.de): Fatal: master: service(lmtp): child 20367 killed with signal 6 (core dumps disabled)