There are a number of factors that determine whether an alert message will be sent and to whom it will be sent.

Filters

When you create a device, a default filter is automatically applied to all devices.  The default filter requires that more than one location (unless you only select one location) receives the error before an alert is triggered.  This is done to eliminate false positive alerts when one location suffers from a small network hiccup.  You can create a filter that does not require more than one location, but be aware that you will likely receive many false positive alerts due to the uncontrolled nature of traffic on the internet.

Schedules

If you have applied a schedule to a device, the device will not be monitored during unscheduled periods, so no data will be recorded to set off an alert.  We recommend that you do not apply a schedule directly to your devices so that the system is monitored 24/7 even if you do not wish to receive alerts around the clock.  You can apply schedules to different alert groups so that different groups only receive alerts during their work shifts, for example.

Escalation periods

When setting up group alerts, you can specify whether the group should receive a notification immediately when the error is detected, or if there should be a delay between when the error is first detected and when an error is sent.  For example, perhaps you have a second tier support group that is only notified when an error continues to occur 30 minutes after the first tier support received an alert.

False Positive checks

By default, the False positive check is turned on.  This means that if a monitoring location experiences an error, it attempts to recreate the error before sending an error message.  We do not recommend disabling this because it will increase the risk of receiving false positive alerts, however, if your task takes a particularly long time to complete one iteration, you may wish to turn off the false positive check so that you receive errors immediately rather than 10 minutes after the first error was detected (5 minutes to complete the first task, then when the error is detected, another 5 minutes to confirm the error)

Alert Groups

Note that Alert groups can be set up and used for multiple devices.  If you notice that someone is not receiving an alert, make sure that their contact information exists in all groups necessary.  Be careful when editing or removing people from groups because that group may be used for additional devices.