mailx default FROM: address

Question

I'm setting up email alert for unattended upgrades on ubuntu 18.04. It looks like unattended-upgrades cannot set the 'FROM' address and rely on mailx.

On mailx I'm using SMTP so the from address must be qualified. I get error that the from address is root and not root@mydomain.com

To change this I need to set the 5th parameter in the root user in /etc/passwd file.

Is there no other less intrusive option?

EDIT: Adding ssmtp definitions (changed domain and user/pass for security)

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=nir@domain.com

# The place where the mail goes. The actual machine name is required no 
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=email-smtp.eu-west-1.amazonaws.com:587

# Where will the mail seem to come from?
rewriteDomain=domain.com

# The full hostname
hostname=domain.com

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES


# Use SSL/TLS before starting negotiation
TLS_CA_FILE=/etc/ssl/certs/ca-certificates.crt
UseTLS=NO
UseSTARTTLS=YES




AuthUser=XXX
AuthPass=YYY
AuthMethod=LOGIN

# sSMTP aliases
# 
# Format:   local_account:outgoing_address:mailhub
#
# Example: root:your_login@your.domain:mailhub.your.domain[:port]
# where [:port] is an optional port number that defaults to 25.

root:nir@domain.com:email-smtp.eu-west-1.amazonaws.com:587

It is usually up to the mail server to complete unqualified e-mail addresses. Which server are you using? — Piotr P. Karwasz, Jan 21 '20 at 09:45
@PiotrP.Karwasz AWS SES. It requires qualified sender address. — Niro, Jan 21 '20 at 10:27
I use ssmtp to send the emails. I dont think I run a full e-mail server — Niro, Jan 21 '20 at 10:46
Can you add your **ssmtp** configuration? It is his job to rewrite unqualified addresses to full addresses. — Piotr P. Karwasz, Jan 21 '20 at 15:11
I don't use **ssmtp**, but I'd change `FromLineOverride` to `NO`. — Piotr P. Karwasz, Jan 22 '20 at 12:06

score 1 · Answer 1 · answered Dec 29 '21 at 20:42

On Debian, I have found that using mailx command from the mailutils package generates wrong "From" domain address - it calls sendmail with "-f" parameter specifying just the hostname without any domain.

When you install the bsd-mailx package, it provides its own version of the mail / mailx binary (which should be set automatically as the default alternative). This internally calls "sendmail" without the "-f" parameter and (when mail server is configured properly) uses the correct full hostname + domain.

mailx default FROM: address

1 Answers1