Since both of the users specified in the action operations have explicitly been denied access to the snmptraps host, they were not considered valid for action operations.

Let's give them access to this host now:

1. Go to Administration | User groups and click on Our users in the Name column.
2. Switch to the Permissions tab, then mark the read-write box in Important SNMP hosts, and then click on Update. Both users should now have access to the desired host.

Out triggers have been deactivated by now, so we can send another trap to activate the one on the snmptraps host.

Run the following commands on Another host:

$ snmptrap -Ci -v 2c -c public <Zabbix server> "" "NET-SNMP-MIB::netSnmpExperimental" NET-SNMP-MIB::netSnmpExperimental s "Critical Error"  

Wait for a while so that the trigger fires again. Check your email, and you should have received a notification regarding the host that we were previously not notified about, snmptraps. Let's see the event list again. Open Monitoring | Problems and look at the latest entry.

Oh, but what's up with the weird entry in the Actions column? Those two differently colored numbers look quite cryptic. Let's try to find out what they could mean by opening Reports | Action log and looking at the last few entries:

The STATUS column says that sending the message succeeded for the monitoring_user, but failed for the advanced_user. Thus, green numbers in the event list mean successfully sent notifications, while red numbers mean failures. To see why it failed, move the mouse cursor over the red X in the INFO column:

You can click the red X to make the popup stay when the mouse cursor moves away, which allows us to copy the error text.

Excellent—that clearly explains what the error is; our advanced_user had no media entries defined. We can easily deduce that numbers in the event list represent notification counts—green for successful ones and red for unsuccessful ones. It also shows us that actions should not be configured to send messages for users that do not have media correctly set, as such entries pollute the action log and make it harder to review interesting entries.

While the action log provides more detail, we could have established the error in the event list as well. Return to Monitoring | Problems and move the mouse cursor over the red, right-most number 1 in the Actions column. A popup will appear. Click on the number 1 to make the popup stay and move the mouse cursor over the red X in the INFO column. The same informative popup will appear, in this case telling us that there's no media defined for this user.