SMTP server: localhost
SMTP helo: myinternetdomain.com
SMTP email: firstname.lastname@example.org
Add a user with email media notifications. It didn't seem to be enough to have this setting, I also had to add an Action. The triggers were an "AND" of:
(A) Trigger severity >= "High"
(B) Trigger value = "PROBLEM"
with the recovery option ticked this got me a PROBLEM email and a RECOVERY email for all triggers above "high". Without the PROBLEM condition I didn't get the recovery message I specified: instead I got two PROBLEM emails with different trigger status (what the?). Others have run into the same issue.
Install postfix and set:
myhostname = myinternetdomain.com
inet_interfaces = 127.0.0.1
You now have a postfix listening on localhost - you can test it with the 'sendmail' terminal command.