ssmtp to email cron output

Cron output in Ubuntu gets discarded. The default install of Ubuntu does not install a Mail Transport Agent (MTA), so cron cannot mail you the output.

You can install an MTA -several are easily available in the Ubuntu repositories- but configuration is not trivial. MTAs date from before the IMAP- and SMTP-based e-mail systems we use today, which makes them highly flexible and configurable...but not necessarily the easiest solution.

ssmtp is a limited-purpose MTA intended to replace the 'mail' command and send all output to an SMTP mailserver. ssmtp is provided by the 'ssmtp' package.

Install

sudo apt-get install ssmtp

Configuration file #1: /etc/ssmtp/ssmpt.conf

This tells ssmtp how to send email to my account.
It's not the best idea to store your e-mail password in world-readable plain text. See how to protect the password properly.

# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=me@example.com

# The place where the mail goes. The actual machine name is required no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=my_mail_server.net:465
AuthUser=me@example.com
AuthPass=my_email_password
UseTLS=Yes

# Where will the mail seem to come from?
rewriteDomain=example.com

# The full hostname
hostname=hey_its_my_computer

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES

Configuration File #2: /etc/ssmtp/

This directs root mail to my account.

# sSMTP aliases
#
# Format:       local_account:outgoing_address:mailhub
#
# Example: root:your_login@your.domain:mailhub.your.domain[:port]
# where [:port] is an optional port number that defaults to 25.
root:me@example.com:my_mail_server.net:465

And now cron output lands in my normal inbox.

Sending e-mail from the command line

I want to send automatic e-mail as a cron job from my Xubuntu 8.04 laptop. Originally, I tried routing it through the legacy mail spools - it is, after all, on the same laptop as my e-mail - but gave up in despair. Thanks to Ubuntu Forums for the info.

1. sudo apt-get install ssmtp heirloom-mailx
   or install ssmtp and nail using Synaptic.
   
2. sudo mousepad /etc/ssmtp/ssmtp.conf to edit the ssmtp config file. Modify or add the following lines to the config file:
   

   mailhub=mail.mymailserver.com
   AuthUser=me@mymailserver.com
   AuthPass=my_mail_password
   

   The nail config file does not need to be changed at all.
3. Using the nail command to send e-mail:
   Tip: Pay close attention to the <RETURN>s and <CTRL+D>s
   First line: nail recipient@address.com<RETURN>
   Second line: Subject: subject<RETURN>
   Third line: E-mail body text<CTRL+D>
   
   Example:
   

   nail me@virusmagnet.com
   Subject: Lotta viruses coming into this account
   I need to stop responding to the spam.

4. Generating e-mail as part of a script or cron job:
   
   Script nail -s "Test 3" recipient@email.com < /tmp/test_email will send the following e-mail.
   

   From: You (automatic)
   To: recipient@email.com
   Subject: Test 3
   Message Body: (read from file /tmp/test_email)

   
   
   nail -s "Test 3" recipient@email.com < /dev/null will send an e-mail with a blank body - good for quick reminders using the subject line only.
   
   To generate e-mail from cron events, use the command crontab -e to edit your crontab file:
   
   26 21 * * * nail -s "Test 3" recipient@email.com < /tmp/test_email
   
   This crontab entry will send the same "Test 3" e-mail every day at 9:26 p.m.

Many elements can be added or customized - this is simple enough to generate automatic e-mails to myself.

UPDATE: September 9, 2008: I could do this in evolution, but it's more fun to use cron and nail or zenity
This crontab entry:

0 6 28 * * /usr/bin/nail -s "Reminder bot: Pay The Store Rent!" me@example.com </dev/null

will send the following e-mail at 6:00 am on the 28th of each month,

From:    me <my computer>
To:      me@example.com
Subject: Reminder bot: Pay The Store Rent!
Date:    Thu, 28 Jul 2008 06:00:01 -0500 
Text:    None

So I won't forget to pay the rent.... It's important.
This sends an e-mail to a known (to nail) e-mail server, so all machines that check the account get the mail.
Alternately, if I want a a pop-up window:

0 6 28 * * DISPLAY=:0.0 /usr/bin/zenity --info --title "Reminder Bot" --text "Pay The Store Rent"

will give me a pop-up window instead, and

0 6 28 * * DISPLAY=:0.0 /usr/bin/zenity --notification --text "Reminder Bot: Pay The Store Rent"

will give me a tiny notification-area icon.