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That was what I thought but I just wanted to be sure. &nbsp;Thank you. &nbsp;
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That was what I thought but I just wanted to be sure.  Thank you.  

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I was given the Exchange Admin position and asked to cleanup the permissions on the public folder. &nbsp;Many users have left the company and this is one task that has been neglected. &nbsp;While trying to clean it up, I found several users that show up as NT User:S-1-5-21-xxxxxxxxx where x could be anywhere from 30 to 35 numbers. &nbsp;Is this some kind of orphaned SID of a user that has since been deleted from Active Directory? &nbsp;Would it cause a problem to delete this user from the folder? &nbsp;Or could this be a username for some application that needs access to the public folder? &nbsp;
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I was given the Exchange Admin position and asked to cleanup the permissions on the public folder.  Many users have left the company and this is one task that has been neglected.  While trying to clean it up, I found several users that show up as NT User:S-1-5-21-xxxxxxxxx where x could be anywhere from 30 to 35 numbers.  Is this some kind of orphaned SID of a user that has since been deleted from Active Directory?  Would it cause a problem to delete this user from the folder?  Or could this be a username for some application that needs access to the public folder?  

Public Folder permissions cleanup

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

Windows Server 2003 was based on Windows XP and was released in four editions: Web, Standard, Enterprise and Datacenter. It also had derivative versions for clusters, storage and Microsoft’s Small Business Server. Important upgrades included integrating Internet Information Services (IIS), improvements to Active Directory (AD) and Group Policy (GP), and the migration to Automated System Recovery (ASR).