msmtp Setup (Debian Jessie)

msmtp inside initramfs

These are files I needed in order to get msmtp running inside my initramfs on Debian Jessie.

I encountered quite a few pitfalls while trying to get this set up, so I wanted to save them here for posterity.

hooks_msmtp

#!/bin/sh

PREREQ="dropbear"

prereqs() {
    echo "$PREREQ"
}

case "$1" in
    prereqs)
        prereqs
        exit 0
        ;;
esac

. "${CONFDIR}/initramfs.conf"
. /usr/share/initramfs-tools/hook-functions

# Install msmtp if explicitly enabled, or in case of a dropbear setup if not
# explicitly disabled
if [ "${MSMTP}" = "y" ] || ( [ "${MSMTP}" != "n" ] && [ -x "${DESTDIR}/sbin/dropbear" ] ); then
    if [ ! -x "/usr/bin/msmtp" ]; then
        if [ "${MSMTP}" = "y" ]; then
            echo "msmtp: FAILURE: msmtp not found!"
        else
            echo "msmtp: WARNING: msmtp not found, you won't be notified via mail when system is booting up!"
        fi
    else
        # Remove old binary, copy new one
        rm -f "${DESTDIR}/bin/msmtp"
        copy_exec "/usr/bin/msmtp" "/bin/"
        # Remove old configuration, copy new one
        rm -f "${DESTDIR}/root/.msmtprc"
        cp /etc/initramfs-tools/root/.msmtprc "${DESTDIR}/root/"
        # Copy resolv.conf, for DNS lookups
        cp /etc/resolv.conf "${DESTDIR}/etc/"
        # Copy libraries needed for DNS lookups
        cp /lib/x86_64-linux-gnu/libnss_dns.so.2 "${DESTDIR}/lib/x86_64-linux-gnu/"
        cp /lib/x86_64-linux-gnu/libnss_files.so.2 "${DESTDIR}/lib/x86_64-linux-gnu/"
        cp /lib/x86_64-linux-gnu/libresolv.so.2 "${DESTDIR}/lib/x86_64-linux-gnu/"
        # Copy certificates
        mkdir -p "${DESTDIR}/etc/ssl/certs/"
        cp /etc/ssl/certs/ca-certificates.crt "${DESTDIR}/etc/ssl/certs/"
    fi
fi

root_.msmtprc

defaults
tls on
tls_starttls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

account gmail.com
host smtp.gmail.com
port 587
auth on
user <email>
password <password>
from <email>
syslog off
logfile

scripts_local-top_msmtp

#!/bin/sh

PREREQ="dropbear udev devpts"

prereqs() {
    echo "$PREREQ"
}

case "$1" in
    prereqs)
        prereqs
        exit 0
    ;;
esac

. /scripts/functions

[ -x /bin/msmtp ] || exit 0

log_begin_msg "Sending mail"

. /conf/initramfs.conf

configure_networking

echo -e "Subject: Server '<server>' has rebooted\nServer '<server>' has rebooted, and is awaiting unlocking before it can continue booting." | /bin/msmtp --file=/root/.msmtprc --account gmail.com -- <destemail>