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Hi,<br />
<br />
I'm using Exchange Server 2010 SP3 and during the health check, I noticed that the following event is logged intermittently (random) no specific pattern:<br />
<br />

<blockquote>
<br />
Log Name: &nbsp; &nbsp; &nbsp;Application<br />
Source: &nbsp; &nbsp; &nbsp; &nbsp;MSExchange ADAccess<br />
Date: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;12/04/2015 2:17:28 PM<br />
Event ID: &nbsp; &nbsp; &nbsp;2156<br />
Task Category: Validation<br />
Level: &nbsp; &nbsp; &nbsp; &nbsp; Error<br />
Keywords: &nbsp; &nbsp; &nbsp;Classic<br />
User: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;N/A<br />
Computer: &nbsp; &nbsp; &nbsp;PRODHTCAS01-VM.domain.com<br />
Description:<br />
Process w3wp.exe () (PID=4516). Recipient object CN=dummy user2,OU=Old Employees,DC=domain,DC=com<wbr /> read from DC2k3-02-VM.domain.com failed validation. A data validation exception will be given. &nbsp;Set event logging level for Validation category to Expert to get additional events about each failure.
</blockquote>
<br />
So I wonder if this is a real security issue from external people or this is can be ignored after deleting the user account drom AD console ?
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Hi,

I'm using Exchange Server 2010 SP3 and during the health check, I noticed that the following event is logged intermittently (random) no specific pattern:


Log Name:      Application
Source:        MSExchange ADAccess
Date:          12/04/2015 2:17:28 PM
Event ID:      2156
Task Category: Validation
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      PRODHTCAS01-VM.domain.com
Description:
Process w3wp.exe () (PID=4516). Recipient object CN=dummy user2,OU=Old Employees,DC=domain,DC=com read from DC2k3-02-VM.domain.com failed validation. A data validation exception will be given.  Set event logging level for Validation category to Expert to get additional events about each failure.

So I wonder if this is a real security issue from external people or this is can be ignored after deleting the user account drom AD console ?

Test account reported as MSExchange ADAccess error ?

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Active Directory (AD) is a Microsoft brand for identity-related capabilities. In the on-premises world, Windows Server AD provides a set of identity capabilities and services, and is hugely popular (88% of Fortune 1000 and 95% of enterprises use AD). This topic includes all things Active Directory including DNS, Group Policy, DFS, troubleshooting, ADFS, and all other topics under the Microsoft AD and identity umbrella.

Active Directory

Operating system security (OS security) is the process of ensuring OS integrity, confidentiality and availability. OS security refers to specified steps or measures used to protect the OS from threats, viruses, worms, malware or remote hacker intrusions. OS security encompasses all preventive-control techniques, which safeguard any computer assets capable of being stolen, edited or deleted if OS security is compromised, including authentication, passwords and threats to systems and programs.