UnhealthyMailboxDeliveryAvailabilityMonitor

Hello

In our Exchange 2013 deployment I can see on all Mailbox servers MailboxDeliveryAvailabilityMonitor reported as unhealthy

Name                    : MailboxDeliveryAvailabilityMonitor
TargetResource          :
HealthSetName           : MailboxTransport
HealthGroupName         : ServiceComponents
AlertValue              : Unhealthy

In the event log under Active Monitoring -> Probe Results are the visible errors like this:

   ResultId 117170212
 
   ServiceName MailboxTransport
 
   ResultName MailboxDeliveryInstanceAvailabilityProbe/MBX200-02
 
   WorkItemId 884
 
   MachineName XXXXX
 
   Error A TLS API failure occurred. Error = 0x80090301
 
   Exception Microsoft.Exchange.Net.ExSmtpClient.TlsApiFailureException: A TLS API failure occurred. Error = 0x80090301 at Microsoft.Exchange.Net.ExSmtpClient.SmtpSslStream.SmtpSslHelper.Encrypt(Byte[] bytesToEncrypt, Int32 offset, Int32 numberOfBytesToEncrypt) at Microsoft.Exchange.Net.ExSmtpClient.SmtpSslStream.SmtpSslHelper.Encrypt(Byte[] bytesToEncrypt) at Microsoft.Exchange.Net.ExSmtpClient.SmtpSslStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.IO.Stream.<BeginWriteInternal>b__11(Object param0) at System.Threading.Tasks.Task`1.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.IO.Stream.EndWrite(IAsyncResult asyncResult) at System.IO.Stream.<BeginEndWriteAsync>b__17(Stream stream, IAsyncResult asyncResult) at System.Threading.Tasks.TaskFactory`1.FromAsyncTrimPromise`1.Complete(TInstance thisRef, Func`3 endMethod, IAsyncResult asyncResult, Boolean requiresSynchronization)
 
   StateAttribute11 127.0.0.1
 
   StateAttribute12 2 latencies were above the standard deviation. Mean: 0 Standard Deviation: 1. STARTTLS (2, Two) BeforeConnect (1, One)  
 
   StateAttribute13 BeforeConnect=1;Connect=0;EHLO=0;STARTTLS=2;EHLO=0
 
   StateAttribute14 XXXXX.DOMAIN
 
   StateAttribute15 220 XXXXX.DOMAIN Microsoft ESMTP MAIL Service ready at Wed, 17 Feb 2016 15:20:44 +0100EHLO XXXXX.DOMAIN 250-XXXXX.DOMAIN Hello [127.0.0.1]X-ANONYMOUSTLS 220 2.0.0 SMTP server readyEHLO XXXXX.DOMAIN  
 
   StateAttribute16 475
 
   StateAttribute17 2
 
   StateAttribute21 System.Exception
 
   StateAttribute22 220 2.0.0 SMTP server ready  

   ResultType 4
 
   ExecutionId 54194945
 
   ExecutionStartTime 2016-02-17T14:20:45.0533096Z
 
   ExecutionEndTime 2016-02-17T14:20:45.0583101Z

   ExtensionXml [null]
 
   SampleValue 4.0004
 
   ExecutionContext [null]
 
   FailureContext Server 127.0.0.1 on port 475 did not respond with expected response (OK). The actual response was: 220 2.0.0 SMTP server ready .
 
   FailureCategory -1

This error is logged several times per minute.

Any idea?

Thanks