msmtp is a very simple and easy to use smtp client

sudo pacman -S msmtp msmtp-mta

The /etc/msmtprc file must be created with this content

#Example for a system wide configuration file
 
# A system wide configuration file is optional.
# If it exists, it usually defines a default account.
# This allows msmtp to be used like /usr/sbin/sendmail.
account default
 
# The SMTP smarthost.
host smtp.free.fr
protocol smtp
port 465
 
# Construct envelope-from addresses of the form "user@oursite.example".
#auto_from on
#maildomain oursite.example
from campi@beafrancois.fr
maildomain free.fr
 
auth login
user captain.metal
password xxxxxxxx
 
# Use TLS.
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
tls_starttls off
tls_certcheck on
 
# Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
syslog LOG_MAIL