====== Exim configuration for outgoing emails ======

<code>
apt-get install exim4
</code>

Set/adjust mail name as necessary:
<code>
vi /etc/mailname
</code>

Set aliases to redirect root mail to other email address:
<code>
vi /etc/aliases
</code>
add/amend
<code>
root: postmaster@example.com
</code>
apply new aliases file
<code>
newaliases
</code>

exim seems to use the local user (app-name) www-data without a domain as original sender which some email providers (e.g. emailantidote.com) rejects as valid sender.

Update exim config to set default domain for www-data user:

<code>
vi /etc/email-addresses
</code>
add
<code>
www-data: noreply@example.com
</code>
save and restart exim
<code>
/etc/init.d/exim4 restart
</code>
Now force mail queue:
<code>
exim -qff
</code>

To check the message queue, use
<code>
ls -la /var/spool/exim4/msglog/
</code>

To send via smarthost, generate a smarthost authentication file (replace with actual username/password):
<code>
echo "*:smarthost-login:smarthost-password" > /etc/exim4/passwd.client
</code>

By default, exim does not send external emails. Use the following to set it to send using "smarthost, no local" and ensure to enter the smart host name:
<code>
dpkg-reconfigure exim4-config
</code>

To allow non-tls passwords for the smarthost, use:
<code>
echo "AUTH_CLIENT_ALLOW_NOTLS_PASSWORDS = 1" >> /etc/exim4/exim4.conf.localmacros
</code>

To avoid 'message is too big (transport limit = 1)' error, triggered by some cron output, use:
<code>
echo "IGNORE_SMTP_LINE_LENGTH_LIMIT=1" >> /etc/exim4/exim4.conf.localmacros
</code>

Disable ipv6
<code>
sed -i s/dc_local_interfaces='127.0.0.1 ; ::1'/dc_local_interfaces='127.0.0.1'/g /etc/exim4/update-exim4.conf.conf
update-exim4.conf
</code>

Restart exim using
<code>
service exim4 restart
</code>