RFI: Is it possible to use Sub-Attributes and foreach loops in templates?

[Callidus2000]

Hi,
I'm developing a template based mail library. As one example I've got the following "data gatherer":

$forest = Get-ADForest
$domains = $forest.Domains

$allUsers = foreach ($domain in $domains) {
    Get-ADUser -Server $domain -Filter "mail -like '*'" -Properties givenName,surname,mail,userPrincipalName |
        Select-Object @{Name='Domain';Expression={$domain}},
                      @{Name='FirstName';Expression={$_.givenName}},
                      @{Name='LastName';Expression={$_.surname}},
                      @{Name='Mail';Expression={$_.mail}},
                      @{Name='UPN';Expression={$_.userPrincipalName}}
}

# Group by mail address and create array with required structure
$userArray = $allUsers | Group-Object -Property Mail | ForEach-Object {
    $firstUser = $_.Group | Select-Object -First 1
    [PSCustomObject]@{
        Mail      = $_.Name
        FirstName = $firstUser.FirstName
        LastName  = $firstUser.LastName
        UserList  = $_.Group
    }
}

I'd like to use a template which creates a mail with a list of all users, but the loop is the problem (see it as pseudo code):

# Hello þFirstNameþ þLastNameþ,

Below you will find a list of your accounts grouped by domain:


## Accounts by Domain
þ{UserList | ForEach-Object {
    "### Domain: $($_.Domain)"
    "- UPN: $($_.UPN)"
} | Join-String -Separator "`n"}þ

Best regards,
Your IT Team

-Sascha aka callidus2000