JP Vossen on 23 Mar 2011 00:19:03 -0700

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[PLUG] nullmailer & ssmtp

Monday night at PLUG W we were talking about ways to get mail (e.g., cron job failures, logchecks, low disk) from machines that aren't mail servers. Sure you can install Sendmail (shudder :) or Postfix, but that's a lot of attack surface, resource overhead and configuration overhead you don't need or want.

Instead, just use 'nullmailer' on Debian/Ubuntu, or 'ssmtp' on CentOS/RHEL.

### RPM-ish (Red Hat, Suse)
$ yum -C info ssmtp
Loaded plugins: fastestmirror
Installed Packages
Name       : ssmtp
Arch       : x86_64
Version    : 2.61
Release    : 15.el5
Size       : 92 k
Repo       : installed
Summary    : Extremely simple MTA to get mail off the system to a Mailhub
URL        :
License    : GPLv2+
Description: A secure, effective and simple way of getting mail off a system to your mail hub. It contains no suid-binaries or other dangerous things - no mail spool to poke around in, and no daemons running in the background. Mail is simply forwarded to the configured mailhost. Extremely easy configuration.

WARNING: the above is all it does; it does not receive mail, expand aliases or manage a queue. That belongs on a mail hub with a system administrator.

### APT-ish (Debian/Ubuntu)
$ apt-cache show nullmailer
Package: nullmailer
Priority: extra
Section: mail
Installed-Size: 280
Maintainer: Norbert Tretkowski <>
Architecture: i386
Version: 1:1.04-1.1
Replaces: mail-transport-agent
Provides: mail-transport-agent
Depends: libc6 (>= 2.7-1), libgcc1 (>= 1:4.1.1), libstdc++6 (>= 4.1.1), debconf (>= 0.5) | debconf-2.0, lsb-base
Recommends: sysklogd | system-log-daemon
Conflicts: lsb, mail-transport-agent, suidmanager (<< 0.52)
Filename: pool/main/n/nullmailer/nullmailer_1.04-1.1_i386.deb
Size: 90624
MD5sum: 8dd3d0b89d4c8339d45e5186d20e1551
SHA1: 0a02e77c7ed04f13b917dd11a6dd8dd06bf00686
SHA256: c63099b79ac72b1497ac8c69a469ee58d89d41b9b72be3bba427afcee74f2908
Description: simple relay-only mail transport agent
 Nullmailer is a replacement MTA for hosts, which relay to a fixed set
 of smart relays. It is designed to be simple to configure and
 especially useful on slave machines and in chroots.
 The sendmail interface of this package doesn't provide the -bs switch,
 hence it's not LSB compatible!
Tag: interface::daemon, mail::transport-agent, network::server, protocol::smtp, role::program, works-with::mail

JP Vossen, CISSP            |:::======|
My Account, My Opinions     |=========|
"Microsoft Tax" = the additional hardware & yearly fees for the add-on
software required to protect Windows from its own poorly designed and
implemented self, while the overhead incidentally flattens Moore's Law.
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