Using a transactional email service
Add the following properties if you want to use a service like Mailgun, Sendgrid, or Mandrillapp as your SMTP server.
Configuration
Mandrill
grails.mail.enabled=true
grails.mail.debug=true
grails.mail.from=<from-email>
grails.mail.host=smtp.mandrillapp.com
grails.mail.port=587
grails.mail.username=<username>
grails.mail.password=<password>
Sendgrid
grails.mail.enabled=true
grails.mail.debug=true
grails.mail.from=<from-email>
grails.mail.host=smtp.sendgrid.net
grails.mail.port=587
grails.mail.username=<username>
grails.mail.password=<password>
Gmail
grails.mail.enabled=true
grails.mail.debug=true
grails.mail.from=<from-email>
grails.mail.host=smtp.gmail.com
grails.mail.port=465
grails.mail.username=<your-username>
grails.mail.password=<password-generated-from-google-accounts>
grails.mail.props=["mail.smtp.auth":"true", "mail.smtp.socketFactory.port":"465", "mail.smtp.socketFactory.class":"javax.net.ssl.SSLSocketFactory", "mail.smtp.socketFactory.fallback":"false"]
NOTE: I have not been able to able to get the Gmail configuration to work, but I'm sure someone with more time and intelligence will have no trouble figuring it out.
Using local SMTP (not recommended)
Install postfix
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-14-04
Configuration
The default email configuration properties.
grails.mail.enabled = true
grails.mail.debug = true
grails.mail.from = info@openboxes.com
grails.mail.prefix = [OpenBoxes]
grails.mail.host = localhost
grails.mail.port = 25
# These are commented out on purpose.
#grails.mail.username = <username>
#grails.mail.password = <password>