+
+# Program to install and configure Ian's email related programs
+# Copyright (C) 2024 Ian Kelling
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+# todo:
+# on bk (and fsf servers that run multiple exim4 daemons, eg eximfsf2 and eximfsf3),
+# make it so that when exim is restarted due to package upgrades,
+# we also restart those daemons, which can be done like so, based on looking
+# at the prerm and postinst scripts of exim4-daemon-heavy.
+#
+# if [[ ! -e /usr/sbin/invoke-rc.d-diverted ]]; then
+# mv /usr/sbin/invoke-rc.d /usr/sbin/invoke-rc.d-diverted
+# dpkg --divert /usr/sbin/invoke-rc.d-diverted --no-rename /usr/sbin/invoke-rc.d
+# fi
+# /usr/sbin/invoke-rc.d:
+# #!/bin/bash
+# if [[ DPKG_MAINTSCRIPT_PACKAGE == exim4* && $1 == exim4 ]]; then
+# shift
+# ret=0
+# for daemon in exim4 eximfsf2 eximfsf3; do
+# /usr/sbin/invoke-rc.d-diverted $daemon "$@" || ret=$?
+# done
+# else
+# /usr/sbin/invoke-rc.d-diverted "$@"
+# fi
+
+# Things I tend to forget. on MAIL_HOST, daemon runs with /etc/exim4/my.conf,
+# due to /etc/default/exim4 containing:
+# COMMONOPTIONS='-C /etc/exim4/my.conf'
+# UPEX4OPTS='-o /etc/exim4/my.conf'
+#
+# The non-daemon config
+# gets generated from this script calling update-exim4.conf -d /etc/myexim4
+# which has log path
+# log_file_path = /var/log/exim4/my%s
+#
+# On non bk|MAIL_HOST, the config and log file are all standard.
+#
+# eximbackup folder is /bu/md
+# it is cleaned up by mail-backup-clean, which is run by btrbk-run
+
+# shellcheck disable=SC2254 # makes for a lot of unneeded quotes
+
+
+# perusing through /el/mainlog without test messages:
+# &!testignore|jtuttle|
+#
+#&! testignore|jtuttle|eximbackup|/usr/sbin/exim4 -bpu
+
+# todo: this message seems to get dropped on the floor, it was due to a missing 2nd colon in
+# condition = ${if def:h_fdate:}
+# Figure out how to avoid this message being discarded.
+
+# 2023-09-12 01:41:43 [722371] 1qfw9f-0031v9-0S <= ian@iankelling.org U=iank P=local S=483 id=87cyyogd7t.fsf@iankelling.org T="iank2" from <ian@iankelling.org> for testignore@amnimal.ninja
+# 2023-09-12 01:41:43 [722373] 1qfw9f-0031v9-0S H=nn.b8.nz [10.173.8.2]: SMTP error from remote mail server after pipelined end of data: 451 Temporary local problem - please try later
+# 2023-09-12 01:41:43 [722372] 1qfw9f-0031v9-0S == testignore@amnimal.ninja R=smarthost T=remote_smtp_smarthost defer (-46) H=nn.b8.nz [10.173.8.2] DT=0s: SMTP error from remote mail server after pipelined end of data: 451 Temporary local problem - please try later