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

# ------------------------------------------------------------------------------#

Found 2 things today on this when trying msmtp for the first time.

1. 
   

   /etc/aliases default of postmaster: root gave things heartburn. Only revealed by msmtp -v

   
   
   
   
   
   • solved by changing line to postmaster: root@somewhere.com
     
   
   
   
   



2. put aliases /etc/aliases in /etc/msmtprc or ~/.msmtprc

So, I had the exact same issue when I migrated from ssmtp to msmtp. The issue is caused by the is_address() function in aliases.c. Basically, if the target of the alias doesn't contain '@', msmtp thinks it's invalid and dies. You can work around this by just appending @ to all the aliases that redirect to root.

In your example, you would modify /etc/aliases as follows:

# /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

I plan to log a bug/issue against msmtp to get this behavior changed so it just works and will update this answer then.