If you have working smtp server, you can use the below procedure to configure Email notification on GLPI.
GLPI email notification
Login to glpi web interface as admin user
Go to setup -> notifications ->setup and enter your configurations
Use Email Follow-ups – yes
Administrator Email – support@maildomain.com
Email Signature – IT Department
Add a link to GLPI in emails – yes
Base URL used – http://support.example.com
Use a SMTP server to send emails – SMTP (select relevant config)
SMTP Host – your mail server ip
SMTP Login (optional) – user (If smtp auth is enabled for your server requires use proper mail user. Leave blank if no authentication required)
SMTP Password (optional) – mailpassword
Notification and Alarms options can be default.