Send mails from command-line
Being able to send emails from command-line from a server is quite useful when you need to generate emails programatically from shell scripts or web applications for example.
This tutorial explains, how to use to the mail command on linux to send mails from the command-line using the mail command.
How the mail command works
For those who are curious about how exactly the mail command delivers the mails to the recipients, here is a little quick explanation.
The mail command invokes the standard sendmail binary (/usr/sbin/sendmail) which in turns connects to the local MTA to send the mail to its destination. The local MTA is a locally running smtp server that accepts mails on port 25.
mail command -> /usr/sbin/sendmail -> local MTA (smtp server) -> recipient MTA (and Inbox)
This means that an smtp server like Postfix should be running on the machine where you intend to use the mail command. If none is running you get the error message "send-mail: Cannot open mail:25".
Install the mail command
The mail command is available from many different packages. Here is the list -
1. gnu mailutils
2. heirloom-mailx
3. bsd-mailx
2. heirloom-mailx
3. bsd-mailx
Each flavor has a different set of options and supported features. For example the mail/mailx command from the heirloom-mailx package is capable of using an external smtp server to send messages, while the other two can use only a local smtp server.
In this tutorial we shall be using the mail command from the mailutils package, which is available on most Debian and Ubuntu based systems.
Use the apt-get command to install it
$ apt-get install mailutils
Now you should have the mail command ready to work.
1. Use the mail command
Run the command below, to send an email to someone@example.com. The s option specifies the subject of the mail followed by the recipient email address.
$ mail -s "Hello World" someone@example.com
The above command is not finished upon hitting Enter. Next you have to type in the message. When you're done, hit 'Ctrl-D' at the beginning of a line
$ mail -s "Hello World" someone@example.com Cc: Hi Peter How are you I am fine Good Bye <Ctrl+D>
The shell asks for the 'Cc' (Carbon copy) field. Enter the CC address and press enter or press enter without anything to skip.
From the next line type in your message. Pressing enter would create a new line in the message. Once you are done entering the message, press . Once you do that, the mail command would dispatch the message for delivery and done.
2. Subject and Message in a single line
To specify the message body in just one line of command use the following style
$ mail -s "This is the subject" somebody@example.com <<< 'This is the message'
Or like this
$ echo "This is the body" | mail -s "Subject" -aFrom:Harry\<harry@gmail.com\> someone@example.com
3. Take message from a file
If the email message is in a file then we can use it directly to send the mail. This is useful when calling the mail command from shell scripts or other programs written in perl or php for example.
$ mail -s "Hello World" user@yourmaildomain.com < /home/user/mailcontent.txt
Or a quick one liner
$ echo "This is the message body" | mail -s "This is the subject" mail@example.com
4. Specify CC and BCC recipients
Other useful parameters in the mail command are:
-c email-address (CC - send a carbon copy to email-address) -b email-address (BCC - send a blind carbon copy to email-address)
Here's and example of how you might use these options
$ mail -s "Hello World" user1@example.com -c usertocc@example.com -b usertobcc@example.com
5. Sending to multiple recipients
It is also possible to specify multiple recipients by joining them with a comma.
$ mail -s "Hello World" user1@example.com,user2@example.com
6. Specify the FROM name and address
The "-a" option allows to specify additional header information to attach with the message. It can be used to provide the "FROM" name and address. Here is a quick example
# echo "This is the message body" | mail -s "This is the subject" mail@example.com -aFrom:sender@example.com
The a option basically adds additional headers. To specify the from name, use the following syntax.
$ echo "This is the body" | mail -s "Subject" -aFrom:Harry\<harry@gmail.com\> someone@example.com
Note that we have to escape the less/great arrows since they have special meaning for the shell prompt. When you are issuing the command from within some script, you would omit that.
7. Send mail to a local system user
To send mail to a local system user just use the username in place of the recipient address
$ mail -s "Hello World" username
You could also append "@hostname" to the username, where the hostname should be the hostname of the current system.
8. Verbose output
Sometimes when testing mail servers, you would want to check the SMTP commands being used by the mail command. Use the "-v" option for that
$ mail -v -s "This is the subject" somebody@example.com <<< 'This is the message'
If the mail fails to deliver due to an improperly configured mail server for example, the smtp command log will show what has gone wrong.
Send mail with attachments using Mutt
The mail command could do some basic things till now, but moving forward, it lacks important features like sending attachments.
So we have to use another command line tool called mutt. Mutt is like an enhanced version of the mail command with a very similar syntax.
Debian / Ubuntu users can install mutt with the apt command.
$ apt-get install mutt
Fedora / CentOS or Red Hat Enterprise Linux (RHEL) users:
$ yum install mutt
Now you are ready to send mail with attachments with command line interface.
Send a simple mail
$ echo "This is mutt from universe" | mutt -s "This is mutts subject" someone@example.com
Send mail with attachment
Use the "a" option to specify the path of the file to attach
$ mutt -s "Subject" -a /path/to/file -- user@example.com < home/user/mailcontent.txt
According to the syntax of mutt options, it is necessary to separate the files and the recipients with a double dash "--". Also the "-a" option should be last one.
Send mail with bash/shell scripts
This example demonstrates how the output of a command can be used as the message in the email.
Here is an easy shell script that reports disc usage over mail.
Here is an easy shell script that reports disc usage over mail.
#!/bin/bash du -sh | mail -s "disk usage report" user@yourmaildomain.com
Open a new file and add the lines above to that file, save it and run on your box. You will receive an email that contains "du -sh" output.
Read mails
This is not something interesting and you would not be doing this in a real life scenario. It is just being shown for the sake of it.
The mail command can be used to read mails. Just run it without an options and it would list all the mails in your inbox
Here's a sample output
$ mail Heirloom mailx version 12.5 6/20/10. Type ? for help. "/var/mail/enlightened": 7 messages 3 unread O 1 Enlightened Sat Dec 6 11:33 21/658 This is the subject O 2 Enlightened Sat Dec 6 11:34 773/25549 This is the subject O 3 Enlightened Sat Dec 6 16:43 20/633 This is the subject O 4 Enlightened Sat Dec 6 16:44 20/633 This is the subject U 5 Mail Delivery Syst Sat Dec 6 16:50 74/2425 Undelivered Mail Returned to Sender U 6 Enlightened Sat Dec 6 16:51 19/632 This is mutts subject U 7 Enlightened Sat Dec 6 16:52 19/647 This is mutts subject ?
At the end is q question mark which is an interactive prompt waiting for your command. Simply enter the number of the email you want to read and hit enter. It would open up the mail then.
After you are done reading the email, enter 'q' and hit enter to come back. Enter z and hit enter to bring back the list of emails.
The mail command by default reads the emails from the directory "/var/mail/". So every user has a separate mail directory. This way of storing and fetching mails is not very useful or practical in real life, where mail address consist of domain name along with username and a single server could be hosting emails for multiple domains.
Maildir-utils command
'mu' is a set of command-line tools for Linux/Unix that enable you to quickly find the e-mails you are looking for.
Debian/Ubuntu users can use the apt-get command to install it
# apt-get install maildir-utils
To search mails from william with subject report use the following command -
$ mu find from:william subject:report
To check the current mail configurations use the info option.
# mu-tool info VERSION=2.99.97 SYSCONFDIR=/etc MAILSPOOLDIR=/var/mail/ SCHEME=mbox LOG_FACILITY=mail .....
Notes
The mail command is a very basic command to send mails. It should be present and properly configured on any linux server, so that mails are generated and delivered properly.
If you are looking for a more powerful mailing program use commands like mailx, swaks etc. They have the necessary options to specify external smtp servers as well.
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