Relay email to gmail (msmtp, mailx, sendmail

Overview

If you're running an alpine from stick and need a way for your program to alert you through a standard gmail account

Install msmtp

sudo apk add msmtp

Configuration

Create a global configuration, "/etc/msmtprc" with content

# Set default values for all following accounts.
defaults
auth           on
tls            on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
syslog         on

# Gmail
account        gmail
host           smtp.gmail.com
port           587
from           <your email>
user           <your gmail account>
password       <your password>

# Set a default account
account default : gmail
aliases        /etc/aliases

Note: Please note I've used the syslog on to send msmtp log to syslog, yet you can use the logfile <log_file_path> if you prefer to log to a file

Note: Please note the aliases /etc/aliases, this will help for mail/sendmail to redirect email to local user (like root) to an external email

Sendmail alias

By default alpine comes with busybox sendmail, msmtp can act as a sendmail alternative including syntax and option, there I create a local.d script to overwrite the busybox link to msmtp.

Create a file "/etc/local.d/msmtp-sendmail.start" with below content:

#!/bin/sh
ln -sf /usr/bin/msmtp /usr/sbin/sendmail

Make it executable

sudo chmod +x /etc/local.d/msmtp-sendmail.start

Mailx and aliases

Install mailx for program that uses mail (like apcupsd for monitoring UPS events)

sudo apk add mailx

Create an "/etc/aliases" file with content:

root: <your external email where all email to root will be sent>

default: <default email>

Testing

Test an email, run

echo -e "Subject: Do you love alpine?\nYes, I do!\n" | msmtp root

Note: root only work if you've setup /etc/aliases, otherwise put any email adress you can check instead of root

Saving the configuration

sudo lbu ci

Hope it helps.