Defect on Un-Resolved Activity Party

Hi All,

Currently I am working on Crm 2016 On-premise(Dev). Client facing Defect while sending Email with Un-Resolved Activity Party On Production Environment(Online Crm 2016) which not able to send Email. Same defect is Reproducible  in Development Environment(Crm 2016 On-premise). Defect Not raising with all Email Id’s Only specific Email, that Email Id is related with Existed Contact, but it’s highlighting As Un Resolved Activity Party. If I update that Contact’s any Field other than Email Address Field(Like fullname etc.,) , System populating that Contact in To Party field in Email and allowing to send.

In Production Environment, Defect raising with Un-resolved activity party which is not related with contact, account and lead. 

    All OOB and Custom Plugins, JavaScript functionalities, Workflow processes and Custom Buttons are disabled, But Defect is reproducible in  Development Environment and Production Environment.  I gone through some Online articles, But not get any relevant info. Currently User Is System Administrator and Customizer. Log info also shared below for reference .

Un-Resolved Activity Party: Email containing email addresses that are not related to any existing CRM Users, Accounts, Contacts, Leads.

Please find issue related Screen shot for reference:

Please find below Log Info:

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=8.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: Contact With Id = 00000000-0000-0000-0000-000000000000 Does Not ExistDetail:

<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">

  <ErrorCode>-2147220969</ErrorCode>

  <ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />

  <Message>Contact With Id = 00000000-0000-0000-0000-000000000000 Does Not Exist</Message>

  <Timestamp>2017-05-16T12:07:06.1639954Z</Timestamp>

  <InnerFault i:nil="true" />

  <TraceText i:nil="true" />

</OrganizationServiceFault>

Thanks

sandy