Ubuntu – How to disable postfix on startup

10.04cronpostfixservicesstartup

I can't get cron to stop spamming me with completed job notifications. It's getting out of hand and starting to clog up my 'real' email server, so I'd like to just disable postfix while I figure out which job isn't going to /dev/null (any help on this is appreciated as well.)

I can stop the service, but everytime I reboot it kicks out all the emails it's been holding on to, and my mail server goes down ago.

How do I keep postfix from starting on boot, and how can I view its held messages?

Best Answer

Postfix is started in init.d, so you can use update-rc.d to disable it on startup:

sudo update-rc.d postfix disable

When you want to enable it again:

sudo update-rc.d postfix enable

Even if it's disabled you can still start it manually with sudo service postfix start.

If update-rc.d is not in your system, you'll have to install the package sysvinit-utils or sysv-rc, or similar (those are for 12.04, I don't remember if 10.04 use the same names).

As for the notifications, usually the email will give you a clue on which job sent it, but if you want to track all jobs run by cron, you can take a look at the crontab and /etc/cron.*. See the section NOTES in man cron for details.

crontab -l
sudo crontab -l
ls -lr /etc/cron.*

You could also check the syslog:

sudo grep -i cron /var/log/syslog

Related Solutions

Ubuntu – By default, what system messages get mailed to root

By default, cron will mail all output from cron jobs to the owner of the job, whether they fail or not. (Root is the owner of the system cron job, and is configured as the mail destination for non-root daemon cron jobs.) Most system cron jobs are carefully written not to produce output unless something is wrong.

Any other program can send mail to root, but not many will in a default Ubuntu install. Things I have seen include

in Debian, some programs will send mail when they are not properly configured, but I have not seen this recently in Ubuntu
mdraid sends mail when an array fails or is restored
apcupsd sends mail when the machine loses AC power
uptimed sends mail when you pass a milestone or record

If you're writing your own cron jobs you can set MAILTO to control where the output is sent. (See also man 5 crontab.)

Cron – How to Make Crontab Email Output

In the end I used sSMTP. It's far, far simpler than either Postfix or sendmail and does the job beautifully.

For future reference, here's how to use sSMTP with Yahoo Mail (don't worry, it's far less complex than it looks):

Use Synaptic to download ssmtp. Alternatively you could run sudo apt-get install ssmtp.
Open the config file at /etc/ssmtp/ssmtp.conf.

Make the config look like this:

root=[yourRealEmail@yahoo.com.au]
mailhub=smtp.mail.yahoo.com:587
FromLineOverride=YES
UseSTARTTLS=YES
AuthUser=[yourRealEmail@yahoo.com.au]
AuthPass=[yourRealYahooPassword]
TLS_CA_File=~/cert.pem

Create the cert.pem file with OpenSSL. I used the command openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 9999 -nodes (more info at How to create a self-signed certificate with OpenSSL). You can stick the file anywhere, but I just chucked it in ~/. Wherever you put it, make sure you point the TLS_CA_File= line in ssmtp.conf to the correct location.
Open the file /etc/ssmtp/revaliases and add the line:
```
[yourPCUsername]:[yourRealEmail@yahoo.com.au]:smtp.mail.yahoo.com:587
```
If you're running as root, I would think you need to add another line replacing your name with 'root'.

That's it, you're good to go! To test, the easiest way (IMO) is to create a file with the following in it:

To: [yourRealEmail@yahoo.com.au]
From: "whateverYaWant" <[yourRealEmail@yahoo.com.au]>
Subject: Some Notifying Email
MIME-Version: 1.0
Content-Type: text/plain

Body of your email goes here! Hello world!

Save and close the file, then to check you don't have the real sendmail installed, run sendmail -V - it should say 'sSMTP'.
Finally, run cat fileWithEmailInIt.txt | sendmail -i -t, then wait a few seconds (10-30) and check your email!

Obviously, replace [yourRealEmail@yahoo.com.au] with your email (without the brackets) and [yourRealYahooPassword] with your Yahoo Mail password (again, without the brackets).

Additional note 1: If you have trouble with Gmail, try option 1 of this answer.
(Thanks to Ben Creasy!)

Additional note 2: If mail is sending from the command line but not through crontab, try changing FromLineOverride to NO in /etc/ssmtp/ssmtp.conf. You can also get more detailed logging by adding Debug=YES to ssmtp.conf - the extra logging goes to /var/log/mail.log.
(Thanks Jakub Kukul!)

How do I keep postfix from starting on boot, and how can I view its held messages?

Best Answer

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Ubuntu – By default, what system messages get mailed to root

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