Ive followed the documentation but cannot get email alerting working. I see nothing in my mail log from Observium and other mailings on the system work without issue (RANCID, using the mail command from shell) so I believe it related to something I am doing wrong in Observium or PHP. It also looks as though whats in config.php.default doesn't match whats documented in the wiki. Ill gladly update it once I figure out which is correct. 

I am running Observium build 0.14.3.5112 on Debian 5.5.35-0

My config.php based on config.php.defaults , which differs slightly from http://www.observium.org/wiki/Configuration_Options#Alert_Settings

$config['poller-wrapper']['alerter']       = TRUE;

$config['alerts']['alerter']['default']['descr']   = "Network Alert";

$config['alerts']['alerter']['default']['type']    = "email";

$config['alerts']['alerter']['default']['contact'] = "noc@mediamath.com";

$config['alerts']['alerter']['default']['enable']  = TRUE;