We need to reconfigure exim4 to enable outgoing email (exim4 got installed earlier as a prerequisite for the mysql server).

# dpkg-reconfigure exim4-config

• Select "internet site; mail is sent and received directly using SMTP" then configure as appropriate for your site.
• Enter the FQDN of your site when asked
• Listen on all IP addresses (i.e., make list blank)
• Other destinations for which mail is accepted: should be made blank
• Domains to relay mail for: should be made blank
• Machines to relay mail for: should be made blank
• Keep num,ber of DNS-queries minimal (Dial-on-Demand): No
• Delivery method for local mail: mbox format in /var/mail/
• Split configuration into small files? No

This is just an example. Mail should be configured however the site needs. The CMS just expects to be able send outgoing email.