Greetings Daggda,
Regarding your last post:
That's not a problem of eMail alerts, but a problem of the alert configuration, which does not execute because you defined a threshold in your template firing conditions. Please check it.
Regarding your first posts:
Being unable to ping your mail domain doesn't mean you have a problem in your network/DNS configuration... maybe this domain is configured to don't reply to ICMP packets... if this is not the case, change this configuration it until you can ping it...
How to do it?... Well... you have a huge list of examples in the web... search one of them.
Once you've fixed this problem...
It could be a problem of your pandora_server.conf configuration... you don't really need to uncomment and fill all the mta fields... if you have postfix or simillar in your Pandora Server machine, you don't need to provide any external mta... use your own in localhost... you could send mails from your own Pandora Server from the command shell...
Try:
echo "test" | mail -s "test subject" destination@mailaddress.com
If this works and you receive the mail, comment all the mta fields except "mta_from":
mta_from sender@mailaddress.com
Save it and restart your Pandora Server.
/etc/init.d/pandora_server restart
Regards.