It’s common request to allow daemons like cron or applications to
send outgoing email to server’s administrator. Instead of configuring
full-blown email server like Postfix you can install lightweight
forwarder to real external SMTP server, while keeping binary
compatibility with traditional Unix sendmail MTA.
Sendmail compatibility is crucial as it is expected by many many applications. Apart from cron, you may need it for PHP
mail() function, Bugzilla mailing feature and many others stuff originating from Linux/Unix universe.
For this tutorial I chose
MSMTP delegating to secured Google Apps (or Gmail) SMTP. However instructions apply to any SMTP.
Google Apps / Gmail SMTP ports
On
Google Support article
you find up-to-date SMTP server address and configuration. Google SMTP
can be accessed only over secured TLS which complicates MSTMP setup a
little.
Get prepared
First off, install MSTMP on your box:
$ sudo apt-get install msmtp
I always start with discovering remote server certificate with
--serverinfo
option. Also, for Gmail I changed default port 465 which never worked
for me to alternative port 587. Your output would be similar to the
following:
$ msmtp --serverinfo --host=smtp.gmail.com --tls=on --tls-certcheck=off --port=587
SMTP server at smtp.gmail.com (ee-in-f109.1e100.net [173.194.65.109]), port 587:
mx.google.com ESMTP y12sm259113106eeb.11
TLS certificate information:
Owner:
Common Name: smtp.gmail.com
Organization: Google Inc
Locality: Mountain View
State or Province: California
Country: US
Issuer:
Common Name: Google Internet Authority
Organization: Google Inc
Country: US
Validity:
Activation time: St 16. únor 2011, 05:38:09 CET
Expiration time: Čt 16. únor 2012, 05:48:09 CET
Fingerprints:
SHA1: DB:A0:2A:07:00:F9:E3:23:7D:07:E7:52:3C:95:9D:E6:7E:12:54:3F
MD5: 02:4C:12:F3:37:1F:0C:C1:EB:10:4B:92:F7:F1:E0:DF
Capabilities:
SIZE 35882577:
Maximum message size is 35882577 bytes = 34,22 MiB
STARTTLS:
Support for TLS encryption via the STARTTLS command
AUTH:
Supported authentication methods:
PLAIN LOGIN
MSMTP configuration
MSMTP can be driven from command line for one-time use, or from user
or system-wide configuration file. Configuration file location is listed
on
--version command.
$ msmtp --version
...
System configuration file name: /etc/msmtprc
User configuration file name: /home/libor/.msmtprc
...
If system configuration file
/etc/msmtprc doesn’t exist, create it
$ sudo touch /etc/msmtprc
Copy’n'paste & customize the following configuration for your
Gmail/Google Apps account. Below I configured one account and again used
alternative port 587. Consult MSMTP
man page for more details.
# Default settings that all others account inherit
defaults
auth on
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
# Logging - uncomment either syslog or logfile, having both uncommented disables logging at all.
#syslog on
# Or to log to log own file
#logfile /var/log/msmtp.log
keepbcc on
# Gmail/Google Apps (configure as may as you want)
account gmail
host smtp.gmail.com
port 587
from your@gmail
user your@gmail
password secretPassword
# Default account to use
account default : gmail
Because this file contains password in plain text you should cut down
its permissions. Let’s make use of group called mail coming from
default Ubuntu installation. Any process which is run under mail group
member can read this file and therefore actually send email.
$ sudo chgrp mail /etc/msmtprc
$ sudo chmod 660 /etc/msmtprc
Add any users who needs to be member of mail group (like your webserver user etc.)
$ sudo adduser www-data mail
$ sudo adduser ... mail
Logging
If not configured differently, MSMTP has logging disabled at all.
Hopefully MSMTP can be set to log to separate log file or syslog,
but not both (it will stop logging).
In
/etc/msmtprc or your user configuration file add/change key
- logfile
/var/log/msmtp.log or whatever file you wish to log into dedicated file OR
-
syslog on to enable syslog logging. Default facility is LOG_USER or specify with syslog .
MSMTP logs to syslog but we want to tweak it to log on startup to
/var/log/msmtp.log instead.
If you log to file, it has to exists prior MSMTP can log into it. Therefore create & set permissions appropriately:
$ sudo touch /var/log/msmtp.log
$ sudo chgrp mail /var/log/msmtp.log
$ sudo chmod 660 /var/log/msmtp.log
Setting PHP to MSMTP
Open file
/etc/php5/apache2/php.ini and change
sendmail_path = "/usr/bin/msmtp -t"
Restart Apache to gain permissions to read MSMTP configuration file and send emails
sudo service apache2 restart
Symlink to sendmail
However MSMTP is binary compatible with sendmail, it doesn’t create
sendmail executable in your path. Applications like Bugzilla has
hard-wired link to sendmail executable and in current setup you will see
error the following error whey you try to send email:
There was an error sending mail from 'bugzilla-daemon@virtage.com' to
'support@virtage.com': Couldn't find 'sendmail' executable in your PATH
and $Email::Send::Sendmail::SENDMAIL is not set.
To fix, symlink MSMTP to common places:
$ ln -s /usr/bin/msmtp /usr/sbin/sendmail
$ ln -s /usr/bin/msmtp /usr/bin/sendmail
$ ln -s /usr/bin/msmtp /usr/lib/sendmail
Try out MSMTP
Always use
-v option to see all SMTP communication. MSMTP reads message body from stdin (as sendmail do).
Create file called e.g.
testmail having the following contents:
To: <username>@domain.com
From: username@gmail.com
Subject: A test
Yadda, yadda, yadda.
And execute
cat testmail | msmtp komu@domain.com
Do not merely use “echo ‘Yadda, yadda, yadda.’” instead of “cat
test.mail”. This causes at least Gmail and Yahoo to deliver the mail
incorrectly. Recipient specified as commandline argument is required
however To recipient from file takes precedence over commandline.
You may also review msmtp.log with e.g.
tail /var/log/msmtp.log
Error “msmtp: account default not found: no configuration file available”
Can you see this error in console or in logs and mail is not actually sent? Check the permissions of
/etc/msmtprc for user running msmtp. This error indicates that a process doesn’t have permission to read configuration file.
Mail command
Many scripts assume existence of
mail command. For Ubuntu it could be installed via
heirloom-mailx package.
Mail offers commandline interface more suitable for scripting then msmtp. Send email with mail program is easy as
echo 'Hi from mail body' | mail -s 'Some subject' 'some@email'
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