Relay Mail with Exim4

Example: Google Mail SMTP. Local hostname is think.

Assumes TLS.

https://wiki.debian.org/GmailAndExim4

apt-get install exim4-daemon-light

cat<<'EOF' > /etc/exim4/update-exim4.conf.conf
dc_eximconfig_configtype='satellite'
dc_other_hostnames='think'
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost='think'
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost='smtp.gmail.com::587'
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='true'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'
EOF

cat<<'EOF' > /etc/exim4/passwd.client
*.google.com:USERNAME@gmail.com:PASSWORD
EOF

chown root:Debian-exim /etc/exim4/passwd.client
chmod 640 /etc/exim4/passwd.client

update-exim4.conf
service exim4 reload

Test (from bob@example.org):

echo 'Test body' | mail -r 'Bob <bob@example.org>' -s 'test subject' alice@example.org
tail /var/log/exim4/mainlog

Flush queue:

exim4 -qff  # flush all mails in queue

List and remove messages from queue:

exim -bp
exim -Mrm $message_id
# e.g. exim -Mrm 1WGRuQ-0007ZD-5D