Bug#962847: exim4: takes forever to send a mail after sleeping

[Rémi Letot]

Package: exim4
Version: 4.94-2
Severity: normal

Dear Maintainer,

I'm using exim4 on a laptop to send email through a smarthost. 

Up to 4.93-16, everything went well. 

Since upgrading to 4.94 (4.94-1 and 4.94-2 display the problem), I have 
noticed delays when trying to send email after the laptop has been sleeping. 

My mail client (emacs) simply gets stuck until I cancel the message, or 
wait long enough.

At first I thought that it simply got stuck, but while testing i noticed 
that the delay is exactly the time that the laptop has been sleeping. 

Here the laptop has been asleep 1 minute and 11 seconds:
2020-06-15 01:17:44 1jkbsm-000Stl-SK <= remi at lybrafox.be H=(sphax) [::1] P=esmtps X=TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256 CV=no S=664 id=87y2ops0do.fsf at sphax
2020-06-15 01:18:55 1jkbsm-000Stl-SK => remi at lybrafox.be R=smarthost T=remote_smtp_smarthost H=mail2.lybrafox.be [37.59.240.190] X=TLS1.2:ECDHE_SECP256R1__RSA_SHA256__AES_256_GCM:256 CV=no DN="CN=mail2.lybrafox.be" A=plain C="250 2.0.0 Ok: queued as 394FB419A4"
2020-06-15 01:18:55 1jkbsm-000Stl-SK Completed

And here it has been asleep exactly 4 minutes 2 seconds:

2020-06-15 01:51:07 1jkcP5-000V8E-MS <= remi at lybrafox.be H=(sphax) [::1] P=esmtps X=TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256 CV=no S=664 id=875zbtqk9i.fsf at sphax
2020-06-15 01:55:09 1jkcP5-000V8E-MS => remi at lybrafox.be R=smarthost T=remote_smtp_smarthost H=mail2.lybrafox.be [37.59.240.190] X=TLS1.2:ECDHE_SECP256R1__RSA_SHA256__AES_256_GCM:256 CV=no DN="CN=mail2.lybrafox.be" A=plain C="250 2.0.0 Ok: queued as 8E27141DEE"
2020-06-15 01:55:09 1jkcP5-000V8E-MS Completed

I didn't test for longer delays, but when I leave the laptop asleep for 
the night, my mail client just stays stuck.

Restarting the exim4 service makes it work again without delay, but does 
not make the stuck messages get delivered. For that I need to manually kill 
the stuck daemons and restart the service.

I reverted to 4.93 for the time being, but it's easy to get back to 4.94 if
you need some testing.

Thanks for your work, 
-- 
Rémi

-- Package-specific info:
Exim version 4.94 #2 built 07-Jun-2020 07:55:58
Copyright (c) University of Cambridge, 1995 - 2018
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2018
Berkeley DB: Berkeley DB 5.3.28: (September  9, 2013)
Support for: crypteq iconv() IPv6 GnuTLS move_frozen_messages DANE DKIM DNSSEC Event I18N OCSP PIPE_CONNECT PRDR SOCKS TCP_Fast_Open
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
Configure owner: 0:0
Size of off_t: 8
Configuration file search path is /etc/exim4/exim4.conf:/var/lib/exim4/config.autogenerated
Configuration file is /var/lib/exim4/config.autogenerated
# /etc/exim4/update-exim4.conf.conf
#
# Edit this file and /etc/mailname by hand and execute update-exim4.conf
# yourself or use 'dpkg-reconfigure exim4-config'
#
# Please note that this is _not_ a dpkg-conffile and that automatic changes
# to this file might happen. The code handling this will honor your local
# changes, so this is usually fine, but will break local schemes that mess
# around with multiple versions of the file.
#
# update-exim4.conf uses this file to determine variable values to generate
# exim configuration macros for the configuration file.
#
# Most settings found in here do have corresponding questions in the
# Debconf configuration, but not all of them.
#
# This is a Debian specific file

dc_eximconfig_configtype='satellite'
dc_other_hostnames='sphax'
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost='sphax'
dc_relay_domains=''
dc_minimaldns='true'
dc_relay_nets=''
dc_smarthost='mail2.lybrafox.be::587'
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='true'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'
mailname:sphax
# /etc/default/exim4
EX4DEF_VERSION=''

# 'combined' -	 one daemon running queue and listening on SMTP port
# 'no'       -	 no daemon running the queue
# 'separate' -	 two separate daemons
# 'ppp'      -   only run queue with /etc/ppp/ip-up.d/exim4.
# 'nodaemon' - no daemon is started at all.
# 'queueonly' - only a queue running daemon is started, no SMTP listener.
# setting this to 'no' will also disable queueruns from /etc/ppp/ip-up.d/exim4
QUEUERUNNER='combined'
# how often should we run the queue
QUEUEINTERVAL='30m'
# options common to quez-runner and listening daemon
COMMONOPTIONS=''
# more options for the daemon/process running the queue (applies to the one
# started in /etc/ppp/ip-up.d/exim4, too.
QUEUERUNNEROPTIONS=''
# special flags given to exim directly after the -q. See exim(8)
QFLAGS=''
# Options for the SMTP listener daemon. By default, it is listening on
# port 25 only. To listen on more ports, it is recommended to use
# -oX 25:587:10025 -oP /var/run/exim4/exim.pid
SMTPLISTENEROPTIONS=''

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.6.0-2-amd64 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=fr_BE.UTF-8, LC_CTYPE=fr_BE.UTF-8 (charmap=UTF-8), LANGUAGE=fr_BE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages exim4 depends on:
ii  debconf [debconf-2.0]  1.5.74
ii  exim4-base             4.94-2
ii  exim4-daemon-light     4.94-2

exim4 recommends no packages.

exim4 suggests no packages.

-- debconf information:
  exim4/drec: