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mail Command in Linux/Unix with 10+ Examples [2020]

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Let’s Learn mail Command in Linux/Unix with Practical Examples :

The mail command in linux/unix is a powerful tool once system administrators get to know their way around it. You can use the shell to monitor processes, automate backups, and parse data.

Some command line utilities can be used for convenience when manipulating applications from the somewhat unfriendly screen. When the need to send an email via the command line option, there are numerous ways to go about it.

In this article, you will learn how to send and read emails using the popular commands and learn how to send mail using a shell script. It is also vital that you learn how to send Linux mail attachments. The root user should is the only authorized user who can install these mail packages.

The Common Mail Package Installations:

Command On Debian/Ubuntu On CentOS/RedHat
mailutils $ sudo apt-get install mailutils # yum install mailx
mutt $ sudo apt-get install mutt # yum install mutt
mpack $ sudo apt-get install mpack # yum install mpack
telnet $ sudo apt-get install xinetd telnetd # yum install telnet-server telnet
curl $ sudo apt-get install curl # yum install curl
sendmail $ sudo apt-get install sendmail # yum install sendmail
swaks $ sudo apt-get install swaks # yum install swaks

Some of the command line options taken by most mail commands are:

  • -s denotes the mail’s subject
  • -a for denoting attachment
  • -c for the copy email address (CC)
  • -b for the blind copy email address (BCC)

1. Using mail command in Linux

The Linux mail command in Linux/Unix is quite popular and is commonly used to send emails from the command line. Mail is installed as part of mailutils and mailx packages on Debian and Redhat systems respectively. The two commands process messages on the command line.
To install mail command in Debian and Ubuntu Systems, run

For RedHat & CentOS systems run

If the command is successfully installed, test the application by using the following format and press enter:

Replace [email protected] with your email address.

After pressing ‘Enter’, you’ll be prompted for a Carbon Copy (Cc:) address.

If you wish not to include a copied address, proceed and hit ‘Enter’
Next, type the message or the body of the Email and hit ‘Enter’

Finally, Press Ctrl + D simultaneously to send the Email.

Alternatively, you can use the echo command to pipe the message you want to send to the mail command in Linux/Unix as shown below.

To send an email to many recipients run

Let’s assume you have the message that you want to send in a text file. How do you send it ?
To accomplish this, run the command below

You can create a text file as shown

Then add content to the file

Finally, send the message content

To send an attachment use the command below

The -a flag defines the file attachment.

2. Using the mailx Command in unix/linux

Mailx is the newer version of Linux mail command and was formerly referred to as nail in other implementations. Mailx has been around since 1986 and was incorporated into POSIX in the year 1992.

Mailx is part of the Debian’s mail compound package used for various scenarios. Users, system administrators, and developers can use this mail utility. The implementation of mailx also takes the same form as the mail command line syntax.

To install mailx in Debian / Ubuntu Systems run

To install mailx in RedHat & CentOS run

You may use the echo command to direct the output to the mail command without being prompted for CC and the message body as shown here:

3. Using the MUTT Command

Mutt is a lightweight Linux command line email client. Unlike the Linux mail command that can do basic stuff, mutt can send file attachments. Mutt also reads emails from POP/IMAP servers and connecting local users via the terminal.
To install mutt in Debian / Ubuntu Systems run

To install mutt in Redhat / CentOS Systems run

Here is how to use it. When using the mutt command, you can send an empty message with the < /dev/null right after the email address.

The mutt command supports the Linux mail attachment by using the –a option in this format.

The above example sends an attachment containing sql logs to the specified email address.
Mutt command recognizes file type and therefore will not send HTML file as plain text. For instance:

4. Using mpack Command

The mpack command is used to encode the file into MIME messages and sends them to one or several recipients, or it can even be used to post to different newsgroups.

To install mpack in Debian / Ubuntu Systems run

To install mpack in Redhat / CentOS Systems run

Using mpack to send email or attachment via command line is as simple as:

5. Using SSMTP Command

The sSMTP command allows the user to send emails from the SMTP server via the command line. For example, to send a test email to [email protected] use the following syntax:

Hit CTRL+D to send the email.

6. Using the telnet Command

Telnet is a favourite of the system Administrators who use it to test remote port connectivity. It can also be used to login to the server remotely. Telnet is useful for Linux network troubleshooting email problems.

To install telnet in Debian/ Ubuntu Systems run

To install telnet in RedHat / CentOS Systems run

To listen to a port, you use the following format:

7. Using Sendmail

This command is another popular SMTP server used in many distributions.

To install sendmail in Debian/ Ubuntu Systems run

To install sendmail in RedHat / CentOS Systems run

You can use the following instructions to send email using the command:

The above command sends a file saved as email.txt in the temp folder.

8. Using the CURL Command

This utility is known for file transfers between servers and supports many protocols like the SMTP, POP3, HTTP, and the FTP. It mainly used because of its native PHP implementation meaning it supports the native server-side scripting language.

To install Curl in Debian/ Ubuntu Systems run

To install Curl in RedHat / CentOS Systems run

Sending an email with CURL will force you to set up the SMTP connection and turn on access for less secure apps.

The above command uses the –-url –-user flags to define SMTP connection settings. When using the –-ssl-reqd flag you must ensure that the connection is running on SSL or TLS. The command option requests the connection to be terminated if the server does not support a secure connection, i.e. SSL /TLS.

The –-mail-from flag specifies a single address that the issued email address should be used to send the mail, in this case it is [email protected]. The –-mail-rcpt flag denotes the recipient address, in our case, the mail will be delivered to [email protected] . You can use this flag multiple times for different addresses.

The command option --upload-file is used to transfer the specific file “mail.txt” to a remote URL. If no file name is issued you must use a trailing / after the last directory to indicate no file name was given.

9. Using the Swaks Command

The swaks command is flexible, scriptable and a simple SMTP test utility. Very useful in handling SMTP features like the TLS and authentications.

To install swaks in Debian/ Ubuntu Systems run

To install swaks in RedHat / CentOS Systems run

A simple implementation of the swaks command is to use the following flags:

  • Server –s
  • The user –au
  • The password –ap
  • The address of the recipient
  • The –tls is necessary if you are connecting to port 587

10. Sending Mail from a Shell Script

With all the email command line basics covered, you should be ready to send your first mail using a shell script. Here is an example of a shell script that can send an email. The output of the command sends the status of your PC to the chosen email.

Save the content above on your Linux server and run it to send the output of the df –h command to your email. A better way of sending emails using a shell script is to let the script write the data to a text file and send it to the specified email. For example:

If you can remember the mutt command, here is how you can use it to send attached systems backups. The script below will send the directory as archived and use the mutt command to send it as an attachment. In this case, “echo” is used to add a blank space to the body of the email.

11. How to Read Mails in Linux

Reading emails from the terminal may not be as enjoyable as sending emails. The mail command in linux/unix will give you version of the mail program installed. All Linux messages are installed in personal mailboxes, for example if your name was Linus, your incoming mails will be stored in the /var/spool/mail/ directory. On the other hand, mails sent to the root user are by default sent to the /var/spool/mail/root folder. Reading mails from this folder utilises the command cat in the following format:

The most commonly used syntax utilizes the mail command in this format:

A simple output from the above command gives:

At the end of the output is a question mark that prompts for your input in the form of a command. Key in the number that you want as listed on the screen above and press enter. When done reading, press on letter Q to load the previous screen. When you are entirely done press letter Z followed by the enter key to bring your back to the list of emails. The mail command reads all emails from the “var/mail/” directory. Always make sure that you are reading from the correct user directory if your server hosts multiple domains.
All these commands should get you started with sending emails from the Linux terminal and understand the basic knowledge of using executable shell scripts. More details on these email commands and their respective flags are found on the “man page.”

How to Troubleshoot Mail Problems

Diagnosing email problems covers a broad range of services. Some errors are easy to handle while others may require some sort of analysis. If everything seems to be working okay, the next step is to check the email service logs found in the /var/log/maillog file. To view the last part of an email log, use the tail command line utility (by default tail without any option will give the last ten lines). To set the number of lines to view, use the following format:

The above command displays the last 30 lines of the maillog content. Use the log file to identify any visible error.

Checking mails that are sent through the system can be traced to the /var/spool/postfix directory. Within this directory, there are subdirectories each denoting an active, deferred or bounce state. Here are some of the common commands used when probing email issues:

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