MailboxTransport health set unhealthy (MailboxDeliveryAvailabilityMonitor)

Hi,

I'm getting the following error:

MailboxTransport health set unhealthy (MailboxDeliveryAvailabilityMonitor) - The mail delivery smtp probe failed 5 times over 15 minutes.

I have checked server health and indeed one Probe/Monitor is unhealthy:

CurrentHealthSetState   : NotApplicable
Name                    : MailboxDeliveryAvailabilityMonitor
TargetResource          : 
HealthSetName           : MailboxTransport
HealthGroupName         : ServiceComponents
AlertValue              : Unhealthy
FirstAlertObservedTime  : 9/08/2016 16:05:16
Description             : 
IsHaImpacting           : False
RecurranceInterval      : 0
DefinitionCreatedTime   : 10/08/2016 16:21:05
HealthSetDescription    : 
ServerComponentName     : None
LastTransitionTime      : 9/08/2016 16:21:55
LastExecutionTime       : 10/08/2016 16:24:07
LastExecutionResult     : Succeeded
ResultId                : 231615357
WorkItemId              : 374
IsStale                 : False
Error                   : 
Exception               : 
IsNotified              : False
LastFailedProbeId       : 87
LastFailedProbeResultId : 338511671
ServicePriority         : 0
Identity                : MailboxTransport\MailboxDeliveryAvailabilityMonitor\
IsValid                 : True
ObjectState             : New

I have tried the following command:

Invoke-MonitoringProbe MailboxTransport\MailboxDeliveryAvailability -Server mailbox1.contoso.com | Format-List

But it returns an error:

I have restarted the Health Manager service but this didn't help.

I'm running Exchange 2013 CU8

I read in this article that the MailboxDeliveryAvailability probe is now obsolete. Does it mean I can safely create a monitoring override? 

Many thanks for the help already.

Greetings,

Adriaan