How to actually catch the email address that cannot be found using the below Try/catch block?

Question

The below code will check multiple lines of email address against the Exchange Online as per https://learn.microsoft.com/en-us/powershell/module/exchange/get-exorecipient?view=exchange-ps

Try {
    Clear
    $EmailAliases = @(
        'Myself.actual@domain.com'
        'Good.Boss@domain.org'
        'fake.person1@domain.org'
        'fake.person2@domain.org'
    )

    $EmailAliases | Get-EXORecipient | Select Name, RecipientType, @{Label = 'Email Address'; Expression = {($_.EmailAddresses | Where-Object {($_ -like 'SMTP*') -and ($_ -notlike '*onmicrosoft.com') } | Sort-Object -CaseSensitive -Descending | ForEach-Object {$_.Split(':')[1]}) -join ', ' }} | Out-GridView
}
Catch {
    Write-Warning -Message "The email address $($EmailAliases) cannot be found"
    Write-Warning -Message $Error[0].Exception.Message
    $out.Details = $_.Exception.Message
    Write-Host " ERROR: $($out.Details)" -ForegroundColor Red
}

However, if the email address cannot be found, it is throwing error

Error code:

Get-EXORecipient : Error while querying REST service. HttpStatusCode=404 ErrorMessage={"error":{"code":"NotFound","message":"Error executing request. 
","details":[{"code":"Context","target":"","message":"Ex6F9304|Microsoft.Exchange.Configuration.Tasks.ManagementObjectNotFoundException|The operation couldn't be performed because object 'Fake.person1@domain.org' couldn't be found on 
'NY2PR01A001DC02.NAMPR01A001.PROD.OUTLOOK.COM'."}],"innererror":{"message":"Error executing request. ","type":"Microsoft.Exchange.Admin.OData.Core.ODataServiceException"}}}}
At line:11 char:18
+     $EmailAliases | Get-EXORecipient | Select Name, RecipientType, @{ ...
+                     ~~~~~~~~~~~~~~~~
    + CategoryInfo          : ProtocolError: (:) [Get-EXORecipient], RestClientException
    + FullyQualifiedErrorId : An error occurred while processing this request.,Microsoft.Exchange.Management.RestApiClient.GetExoRecipient

Answer 1

The Identity parameter on Get-EXORecipient takes a single item, not an array of email addresses, so I believe you need a loop do do this.
Also, you do things inside the Try{} block that should not be there, like defining the array of email addresses to test. That is beter done before entering the loop where the try{}..catch{} is doing its job.

Try:

Clear-Host
$EmailAliases = 'Myself.actual@domain.com', 'Good.Boss@domain.org',
                'fake.person1@domain.org', 'fake.person2@domain.org'

$result = foreach ($eml in $EmailAliases) {
    Try {
        Get-EXORecipient -Identity $eml -ErrorAction Stop | 
            Select-Object Name, RecipientType, 
                          @{Name = 'Email Address'; Expression = {
                                ($_.EmailAddresses | 
                                 Where-Object { ($_ -like 'SMTP*') -and ($_ -notlike '*onmicrosoft.com') } | 
                                 Sort-Object -CaseSensitive -Descending | 
                                 ForEach-Object { $_ -replace '^smtp:'}) -join ', ' }
                          },
                          @{Name = 'Details'; Expression = { 'OK' }}
    }
    Catch {
        # inside the Catch block, the $_ automatic variable is the exception object
        Write-Warning -Message "The email address $eml cannot be found"
        $err = $_.Exception.Message
        Write-Warning -Message $err
        # output a similar object as in the catch block showing the failed email address
        "" | Select-Object @{Name = 'Name'; Expression = { 'Not found' }}, RecipientType,
                           @{Name = 'Email Address'; Expression = { $eml }},
                           @{Name = 'Details'; Expression = { $err }}
    }
}

$result | Out-GridView