Bug#840355: Failed to create spool file /var/spool/exim4//input//...-D: Permission denied

[積丹尼 Dan Jacobson]

Package: exim4
Version: 4.88~RC2-1
Severity: grave

Can't send mail, because:
2016-10-11 04:30:53 Failed to create spool file /var/spool/exim4//input//1bthDp-0002gq-Fy-D: Permission denied

-- Package-specific info:
Exim version 4.88 #2 built 09-Oct-2016 15:37:08
Copyright (c) University of Cambridge, 1995 - 2016
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2016
Berkeley DB: Berkeley DB 5.3.28: (September  9, 2013)
Support for: crypteq iconv() IPv6 GnuTLS move_frozen_messages DKIM DNSSEC Event OCSP PRDR SOCKS
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch nis nis0 passwd
Authenticators: cram_md5 plaintext
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore autoreply lmtp pipe smtp
Fixed never_users: 0
Size of off_t: 8
Configuration file is /var/lib/exim4/config.autogenerated
dc_eximconfig_configtype='smarthost'
dc_other_hostnames='jidanni2.jidanni.org;jidanni3.jidanni.org;jidanni4.jidanni.org;jidanni5.jidanni.org;jidanni6.jidanni.org'
dc_readhost='jidanni.org'
dc_relay_domains=''
dc_minimaldns='true'
dc_relay_nets=''
dc_smarthost='homie.mail.dreamhost.com::587'
dc_local_interfaces=''
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='false'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'
mailname:jidanni.org

-- System Information:
Debian Release: stretch/sid
  APT prefers experimental
  APT policy: (990, 'experimental'), (500, 'unstable')
Architecture: i386 (i686)

Kernel: Linux 4.7.0-1-686-pae (SMP w/1 CPU core)
Locale: LANG=zh_TW.UTF-8, LC_CTYPE=zh_TW.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Init: systemd (via /run/systemd/system)

Versions of packages exim4 depends on:
ii  debconf [debconf-2.0]  1.5.59
ii  exim4-base             4.88~RC2-1
ii  exim4-daemon-light     4.88~RC2-1

exim4 recommends no packages.

exim4 suggests no packages.

-- debconf information:
  exim4/drec: