Ubuntu — Send Mail with msmtp

msmtp is a lightweight SMTP client that lets your server send email — useful for cron job failures, script alerts, and unattended-upgrades notifications. It is actively maintained and available in the standard Ubuntu repositories.

Pre-requisites

Ubuntu 22.04+ server
An SMTP account to send through (your mail server, Gmail, Postmark, etc.)
sudo access

Install

sudo apt install msmtp msmtp-mta mailutils -y

msmtp-mta sets msmtp as the system MTA, so tools like mail and cron use it automatically.

Configure

msmtp uses two config files depending on the sending user:

File	Used by
`/etc/msmtprc`	`root` and system services
`~/.msmtprc`	Non-root users

System-wide config (`/etc/msmtprc`)

sudo nano /etc/msmtprc

# Defaults for all accounts
defaults
port 587
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Your mail account
account myserver
host mail.example.com
from server@example.com
auth on
user server@example.com
password YourPassword

# Set this account as default
account default : myserver

Replace mail.example.com, server@example.com, and YourPassword with your actual SMTP credentials.

Restrict read access — the file contains a plaintext password:

sudo chmod 600 /etc/msmtprc

Configure Aliases

Aliases define where system mail (cron errors, failed services) gets delivered. Edit /etc/aliases:

sudo nano /etc/aliases

root: admin@yourdomain.com
default: admin@yourdomain.com

This routes all system mail to your address.

Test

Send a test message:

echo "msmtp is working" | mail -s "Test from $(hostname)" admin@yourdomain.com

Check the log if the mail does not arrive (logging is not enabled by default — add this to /etc/msmtprc to enable it):

logfile /var/log/msmtp.log

Then tail the log after sending:

sudo tail -f /var/log/msmtp.log

Common Issues

Symptom	Cause	Fix
`cannot open mail.example.com:587`	Wrong host or port	Verify SMTP server address and port
`TLS handshake failed`	Certificate mismatch or TLS issue	Check `tls_trust_file` path, try port 465 with `tls_starttls off`
`authentication failed`	Wrong credentials	Double-check username and password; some providers require an app password
No mail received, no error	Aliases not configured	Check `/etc/aliases` and run `newaliases` if needed
Cron jobs don't send mail	`msmtp-mta` not installed	`sudo apt install msmtp-mta`

App passwords

If you use Gmail or Microsoft 365, you likely need to generate an app-specific password. Account passwords are often blocked for SMTP auth by default.