I have configured my Debian server to use msmtp for sending mails. Current use case are for example sending a daily report from logwatch to my isp email.

echo "$body" | mutt -s "$topic" -- "myisp@email.com"

I have configured msmtp by means of a global msmtprc file located at /etc/msmtprc. Contents shown below.

The next thing I want to configure is that my email for my root account (e.g., output from crontabs) is sent to my isp email as well.

I have googled around and found, for example on the Arch wiki, that I should just configure my aliases. Which I have done so at the bottom of the msmtp configuration file.

However, after running newaliases, and trying to execute

echo test | mail -s "test message" root

I get the error

send-mail: /etc/aliases: line 2: invalid address 'postmaster'
Can't send mail: sendmail process failed with error code 78

I am unsure how I can fix this. The alias shown below is what was already present. I only added the gmail address.

I think I could just put a new aliases file but that might break other services that rely on this. I.e., I don't know what the proper way to fix this is.

/etc/aliases

# /etc/aliases
mailer-daemon: postmaster
postmaster: root
nobody: root
hostmaster: root
usenet: root
news: root
webmaster: root
www: root
ftp: root
abuse: root
noc: root
security: root
root: christphe, christophe.detroyer@gmail.com

/etc/msmtprc

# ------------------------------------------------------------------------------
# msmtp System Wide Configuration file
# ------------------------------------------------------------------------------

# A system wide configuration is optional.
# If it exists, it usually defines a default account.
# This allows msmtp to be used like /usr/sbin/sendmail.

# ------------------------------------------------------------------------------
# Accounts
# ------------------------------------------------------------------------------

account isp
host mail.isp.net
port 587
from admin@isp.com
auth login
user admin@isp.com
password foobar
syslog LOG_MAIL

logfile /var/log/msmtp.log

# ------------------------------------------------------------------------------
# Configurations
# ------------------------------------------------------------------------------

# Construct envelope-from addresses of the form "user@oursite.example".
#auto_from on
#maildomain fermmy.server

# Use TLS.
tls on
tls_starttls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
# Must be done within "account" sub-section above
#syslog LOG_MAIL

# Set a default account
account default : isp

aliases /etc/aliases
# ------------------------------------------------------------------------------#