Get-ADUser -SearchBase "ou=ouname,ou=ouname,dc=domainname,dc=suffix" -Filter * | Select-Object -Property Name | Sort-Object{Get-Random} | select -First 10

$timeFrame = (get-Date).AddDays(-90)

get-aduser -SearchBase 'ou=ouname,ou=ouname,dc=domainname,dc=suffix' -Filter * -Properties * |
    Where-Object {$_.whenChanged -gt $timeFrame -and $_.mail -ne $null} |
    Select-Object -Property Name | Sort-Object{Get-Random} | select -First 10

# LastLogontimeStamp is not guaranteed to be updated on every login, so 30 days + 14 days margin
$threshold = (Get-Date).AddDays(-44).ToFileTime()
Get-ADUser -Filter {Enabled -eq $true -and LastLogontimeStamp -gt $threshold} -SearchBase "ou=ouname,ou=ouname,dc=domainname,dc=suffix" | Sort-Object {Get-Random} | Select Name -First 10