When setting up automated backups with rsync and cron, missing email notifications can leave you blind to potential failures. The command structure you're using:

0 23 * * * /usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ | mail -s "Backup Success" admin@example.com

appears correct at first glance, but several technical factors could prevent delivery.

1. Verify Mail System Installation

# Check if mailutils or equivalent is installed
which mail || sudo apt-get install mailutils

2. Test Direct Mail Functionality

echo "Test message" | mail -s "SMTP Test" admin@example.com

3. Check Cron Environment Variables

# View cron's environment
grep -A5 "PATH=" /etc/crontab

Solution A: Full Path Specification

0 23 * * * /usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ 2>&1 | /usr/bin/mail -s "Backup Log" admin@example.com

Solution B: External Script Approach

#!/bin/bash
LOG_FILE=/var/log/backup_$(date +\%Y\%m\%d).log
/usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ > $LOG_FILE 2>&1
if [ $? -eq 0 ]; then
    SUBJECT="Backup Success"
else
    SUBJECT="Backup FAILED"
fi
/bin/mail -s "$SUBJECT" admin@example.com < $LOG_FILE

For enterprise environments, consider these robust alternatives:

# Using mutt with authentication
0 23 * * * /usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ > /tmp/rsync.log 2>&1 && \
/usr/bin/mutt -a /tmp/rsync.log -s "Rsync Report" -- admin@example.com < /dev/null

Or with SSMTP configuration:

# /etc/ssmtp/ssmtp.conf
mailhub=smtp.gmail.com:587
UseSTARTTLS=YES
AuthUser=your@gmail.com
AuthPass=yourpassword
FromLineOverride=YES

Implement comprehensive logging:

# Enhanced cron entry with logging
0 23 * * * /usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ > /var/log/backup.log 2>&1 || \
/usr/bin/mail -s "BACKUP FAILURE $(hostname)" admin@example.com < /var/log/backup.log

Symptom	Diagnostic Command	Solution
No mail received	sudo tail -f /var/log/mail.log	Configure local MTA or use external SMTP
Cron job runs but no output	grep CRON /var/log/syslog	Redirect stderr to stdout with 2>&1
Permission errors	ls -la /usr/bin/mail	Adjust PATH in crontab or use full paths

---

When setting up automated backups using rsync via cron, many sysadmins encounter email delivery issues. The common approach of piping output to mail often fails silently, leaving you unaware of backup status.

The basic command structure:

0 23 * * * /usr/bin/rsync -ravzX /mnt/external/project/ /media/backup/project/ | mail -s "Backup Success" admin@example.com


fails for several technical reasons:

• Missing MTA (Mail Transfer Agent) configuration
• No error handling for failed backups
• Incorrect assumption that rsync output will trigger email

Option 1: Configure Postfix for Local Mail

First install and configure a minimal MTA:


sudo apt-get install postfix mailutils

# Select "Internet Site" during installation

# Test email functionality:
echo "Test message" | mail -s "Test" admin@example.com


Option 2: Wrapper Script with Error Handling

Create /usr/local/bin/backup_notify.sh:


#!/bin/bash

LOG=/var/log/backup.log

echo "Backup started at $(date)" > $LOG

rsync -ravzX /mnt/external/project/ /media/backup/project/ >> $LOG 2>&1

if [ $? -eq 0 ]; then

SUBJECT="Backup Success"

else

SUBJECT="Backup FAILED"

fi

mail -s "$SUBJECT" admin@example.com < $LOG

Make it executable: chmod +x /usr/local/bin/backup_notify.sh

Option 3: Advanced SMTP Configuration

For external SMTP servers, configure /etc/ssmtp/ssmtp.conf:


root=admin@example.com

mailhub=smtp.example.com:587

AuthUser=username

AuthPass=password

UseSTARTTLS=YES


Always verify your setup:


# Check mail queue

mailq

# View mail logs

tail -f /var/log/mail.log

# Test cron job manually

/usr/local/bin/backup_notify.sh


For critical systems, consider supplementing email with:

• Slack/Teams webhooks
• SMS gateways
• Custom monitoring solutions

Example curl notification:


curl -X POST -H 'Content-type: application/json' \

--data '{"text":"Backup completed"}' \

https://hooks.slack.com/services/YOUR/WEBHOOK/PATH