Summary: Cloud and Datacenter Management MVP, Thomas Rayner, shows how use regex to detect if a string is a valid Active Directory user name.
The invalid characters for an Active Directory user name are
“. How do I tell if a string is a valid Active Directory user name?
You can treat this array of characters as a pattern and see if they exist within the string
$questionablestring -match "[$([Regex]::Escape('/\[:;|=,+*?<>') + '\]' + '\"')]"
You’ll have to manually escape
[regex]::escape() is a bit quirky.