[Dovecot] FETCH for mailbox got too little data

[Kenneth Porter]

I've now enabled error logging to a separate log file and see this on 
today's occurrence:

dovecot: Jul 08 09:42:39 Error: IMAP(mortal): Next message unexpectedly 
lost from 41838245
dovecot: Jul 08 09:42:39 Error: IMAP(mortal): Next message unexpectedly 
lost from 41838245
dovecot: Jul 08 09:42:39 Panic: IMAP(mortal): file message-parser.c: line 
770 (message_parser_parse_next_block):
 assertion failed: (ctx->input->eof || ctx->input->closed || 
ctx->input->stream_errno != 0 || ctx->broken)
dovecot: Jul 08 09:42:39 Error: IMAP(mortal): Raw backtrace:
 imap [0x80cfc80] ->
 imap [0x80cfcda] ->
 imap [0x80cf57c] ->
 imap(message_parser_parse_body+0) [0x80c8e00] ->
 imap(index_mail_cache_parse_continue+0x22) [0x8094102] ->
 imap [0x807cd81] ->
 imap(mbox_save_continue+0x38) [0x807ce28] ->
 imap(mail_storage_copy+0xe4) [0x809e5e4] ->
 imap(cmd_copy+0x1d2) [0x805b252] ->
 imap(cmd_uid+0x59) [0x805f4e9] ->
 imap [0x805fe8c] ->
 imap [0x805ff35] ->
 imap [0x80606f5] ->
 imap(client_input+0x5e) [0x806090e] ->
 imap(io_loop_handler_run+0x100) [0x80d75d0] ->
 imap(io_loop_run+0x28) [0x80d6748] ->
 imap(main+0x4ac) [0x806845c] ->
 /lib/libc.so.6(__libc_start_main+0xdc) [0xc2edec] ->
 imap [0x805a271]
dovecot: Jul 08 09:42:39 Error: child 31406 (imap) killed with signal 6