Looking to automate email notifications from your macOS using CRON jobs? This guide walks through configuring Postfix on macOS to send emails from CRON jobs to a designated email address.
Prerequisites
Access to a macOS computer
Basic knowledge of terminal commands
An email account with SMTP access (Gmail used as an example)
Step 1: Verify Postfix Installation
Check whether Postfix is installed:
postconf -d | grep mail_version
Expected output:
mail_version = 3.2.2
milter_macro_v = $mail_name $mail_version
Step 2: Configure Postfix
Edit the main configuration file
Open the Postfix configuration file with superuser privileges:
sudo vi /etc/postfix/main.cf
Add or update the following settings.
SMTP relay configuration (Gmail example)
relayhost = [smtp.gmail.com]:465
Domain configuration
mydomain = example.com
myorigin = $mydomain
Enable SASL authentication
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
TLS configuration
smtp_use_tls = yes
smtp_tls_security_level = encrypt
smtp_tls_note_starttls_offer = yes
smtp_tls_wrappermode = yes
Step 3: Create the SASL Password File
1. Create the credentials file
sudo vi /etc/postfix/sasl_passwd
Add your SMTP credentials:
[smtp.gmail.com]:465 [email protected]:your_password
CRON always sends mail as
[email protected], whereusernameis the user under which the CRON job runs, regardless of the email specified here.
2. Secure and hash the file
sudo postmap /etc/postfix/sasl_passwd
sudo chmod 600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
3. Reload or start Postfix
Reload Postfix:
sudo postfix reload
If Postfix is not running:
postfix/postfix-script: fatal: the Postfix mail system is not running
Start it manually:
sudo postfix start
Step 4: Testing
Example CRON entries:
* * * * * echo "Hello, this is a test from CRON" | sendmail [email protected]
* * * * * bash /path/to/invalid/script
Replace [email protected] with the destination address.
Troubleshooting
- Inspect Postfix logs for errors:
log stream --predicate '(process == "smtpd") || (process == "smtp")' --info --debug
- Ensure the sender account is authorized to relay through the SMTP server.
Conclusion
Postfix is now configured to deliver CRON output via email on macOS, enabling automated monitoring and alerting.
