Linux Mail Command Guide

1. Basic `mail` Command Usage 

1.1 Send an Email 

mail -s "Subject" recipient@example.com

Type the message, then press Ctrl+D to send.

Example:

mail -s "Hello" user1@example.com
This is a test email.
(Press Ctrl+D)

1.2 Send from a File 

mail -s "Subject" recipient@example.com < message.txt

Example:

echo "This is the email body" > body.txt
mail -s "Test Email" user1@example.com < body.txt

1.3 Specify Sender (From Address)

mail -s "Subject" -r "sender@example.com" recipient@example.com

Example:

mail -s "Meeting" -r "admin@company.com" user1@example.com

2. Reading Emails with `mail`

2.1 View Your Mailbox 

mail

Commands inside mail: - Enter → View next message. - d <num> → Delete message (e.g., d 1). - u <num> → Undelete message. - q → Quit (saves changes). - x → Quit (discards changes).

2.2 View Another User’s Mail (as Root)

sudo mail -u username

Example:

sudo mail -u alice

3. Advanced `mail` Command Options 

3.1 Send to Multiple Recipients 

mail -s "Subject" user1@example.com,user2@example.com

Example:

mail -s "Team Update" alice@example.com,bob@example.com

3.2 Add CC and BCC 

mail -s "Subject" -c "cc@example.com" -b "bcc@example.com" recipient@example.com

-c → Carbon Copy.
-b → Blind Carbon Copy (hidden from others).

3.3 Attachments (Using `uuencode`)

uuencode file.txt file.txt | mail -s "File Attached" user@example.com

Example:

uuencode report.pdf report.pdf | mail -s "Report" alice@example.com

4. Scripting with `mail`

4.1 Automated Email from Bash Script 

#!/bin/bash
SUBJECT="System Alert"
TO="admin@example.com"
BODY="Disk space is running low!"

echo "$BODY" | mail -s "$SUBJECT" "$TO"

4.2 Send Command Output via Email 

df -h | mail -s "Disk Usage Report" admin@example.com

Example (send top output):

top -b -n 1 | mail -s "Top Processes" admin@example.com

5. Troubleshooting 

5.1 Check if `mail` is Installed 

which mail

Installation:

Debian/Ubuntu:
```
sudo apt install mailutils
```
RHEL/CentOS:
```
sudo yum install mailx
```

5.2 Check Mail Queue 

mailq # For Sendmail
postqueue -p # For Postfix

5.3 Find Mail Logs 

tail -f /var/log/mail.log # Debian/Ubuntu
tail -f /var/log/maillog # RHEL/CentOS

6. Alternative Mail Clients 

Command	Description
`mutt`	Advanced CLI email client
`alpine`	User-friendly terminal mail
`thunder-` `bird`	GUI mail client

Example using mutt:

sudo apt install mutt # Install
mutt -f /var/mail/$USER # Open mailbox

7. Summary Cheat Sheet 

Command	Description
`mail -s "Sub" user@ex.com`	Send email
`mail -u username`	Read another user’s mail (root)
`echo "Hi" \| mail -s "Test" user@ex.com`	Pipe message
`uuencode file.txt file.txt \| mail ...`	Send attachment
`mailq`	Check mail queue
`tail /var/log/maillog`	Debug mail issues

Notes:

The mail command is lightweight but lacks modern features (e.g., HTML emails).
For scripting, it’s reliable (e.g., cron jobs, alerts).
For advanced usage, consider mutt, sendmail, or Postfix.