unattended-upgrades sends attachment instead of text

Question

I'm trying to setup automatic security updates on Ubuntu Server 12.04 LTS with an email response:

sudo apt-get install unattended-upgrades
sudo dpkg-reconfigure unattended-upgrades
# Answered Yes

The upgrades work, but I get the following email:

Subject: unattended-upgrades result for 'ubuntu' with an empty body and the attachment of unattended-upgrades result for 'ubuntu'.dat

Opening the .dat file in a text editor shows everything, but I'd like to just have this as the body

Here is contents of /etc/apt/apt.conf.d/50unattended-upgrades

// Automatically upgrade packages from these (origin:archive) pairs
Unattended-Upgrade::Allowed-Origins {
        "${distro_id}:${distro_codename}-security";
//      "${distro_id}:${distro_codename}-updates";
//      "${distro_id}:${distro_codename}-proposed";
//      "${distro_id}:${distro_codename}-backports";
};

// Send email to this address for problems or packages upgrades
// If empty or unset then no email is sent, make sure that you
// have a working mail setup on your system. A package that provides
// 'mailx' must be installed.
Unattended-Upgrade::Mail "[email protected]";

Everything else is commented out

Answer 1

Aha, thanks for the raw message, that makes all the difference.

The heirloom-mailx mailer is trying to be helpful; it isn't the unattended-upgrades script itself that is creating the attachments. If you want to keep heirloom-mailx, you can try creating a new configuration file to set the encoding variable to different values, and use the MAILRC environment variable to select the different configuration. Probably some configuration can be found that will just send along the data without any mangling.

Another option would be to use the bsd-mailx version of mailx(1) instead, it is less helpful and will just send raw data.