Check whether username is unique

The script checks whether the username of an account is unique in AD domain and does not match the prefixes of any proxy addresses in Exchange. Usernames are generated as Last Name plus the first initial of the First name. If the current username is not unique the next letter of the first name will be added. To execute the script, create a business rule triggering Before creating a user.

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PowerShell

function IsUniqueInAD($sAMAccountName, $domainName)
{
    $searcher = $Context.BindToObject("Adaxes://$domainName")
    $searcher.Criteria = New-AdmCriteria "user" -Expression {(sAMAccountName -eq $sAMAccountName) -or (proxyAddresses -startsWith $sAMAccountName)}
    $searcher.SearchScope = "ADS_SCOPE_SUBTREE"
    $searcher.SizeLimit = 1
    $searcher.ReferralChasing = "ADS_CHASE_REFERRALS_NEVER"
    
    try
    {
        $searchResultIterator = $searcher.ExecuteSearch()
        $searchResults = $searchResultIterator.FetchAll()
        
        return $searchResults.Length -eq 0
    }
    finally
    {
        # Release resources
        if ($searchResultIterator){ $searchResultIterator.Dispose() }
    }
}

function IsUniqueInExchangeOnline($userName)
{
    # Search users in Exchange Online
    $recipient = Get-Recipient -Filter "EmailAddresses -like 'smtp:$userName@*'" -ResultSize 1 -WarningAction SilentlyContinue
    return $NULL -eq $recipient
}

# Get sAMAccountName
$userName = $Context.GetModifiedPropertyValue("sAMAccountName")

# Connect to Exchange Online
$Context.CloudServices.ConnectExchangeOnline()

# Check whether sAMAccountName is unique
$domain = $Context.GetObjectDomain("%distinguishedName%")
if ((IsUniqueInAD $userName $domain) -and (IsUniqueInExchangeOnline $userName))
{
    return
}
 
# Get the first and last names
$firstName = $Context.GetModifiedPropertyValue("givenName")
$lastName = $Context.GetModifiedPropertyValue("sn")
 
$uniqueUserName = $NULL
for ($i = 2; $i -le $firstName.Length; $i++)
{
    $firstNamePart = $firstName.SubString(0, $i)
    $generatedUserName = "$lastName$firstNamePart"
    if ((IsUniqueInAD $generatedUserName $domain) -and (IsUniqueInExchangeOnline $generatedUserName))
    {
        $uniqueUserName = $generatedUserName
        break
    }
}
 
# If sAMAccountName is not unique, add a digit to it
if ($NULL -eq $uniqueUserName)
{
    for ($i = 1; $True; $i++)
    {
        $uniqueUserName = "$lastName$firstName$i"
        if ((IsUniqueInAD $uniqueUserName $domain) -and (IsUniqueInExchangeOnline $uniqueUserName))
        {
            break
        }
    }
}
 
# Update sAMAccountName
$Context.SetModifiedPropertyValue("sAMAccountName", $uniqueUserName)
 
# Update User Logon Name
$upnSuffix = $Context.GetObjectDomain("%distinguishedName%")
$userLogonName = $uniqueUserName + "@" + $upnSuffix
$Context.SetModifiedPropertyValue("userPrincipalName", $userLogonName)
 
$Context.LogMessage("The username was changed to " + $uniqueUserName + ".", "Information")

Script repository

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