Add alias to Mail in a Box user via PowerShell

$aliaslist=get-content aliaslist.txt

$u="username"
$p="password"
$both="$($u):$($p)"
$encodedcreds=[System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes($both))
$basicAuthValue="Basic $encodedCreds"

$Headers=@{
        Authorization=$basicAuthValue
}

$a=Invoke-RestMethod -Uri https://box.anonit.net/admin/mail/aliases?format=json -Headers $Headers
$a.aliases

foreach ($alias in $aliaslist)
{
    $alias=$alias+"@anonit.net"
    write-output $alias
    $header=@{
        "Authorization"="$basicAuthValue"
        "address"="$alias"
        "forwards_to"="[email protected]"
        "permitted_senders"="[email protected]"
        "update_if_exists"="0"

    }
    $parambody=@{
            "address"="$alias"
            "forwards_to"="[email protected]"
    }
    $AliasResponse=Invoke-RestMethod -Uri https://box.anonit.net/admin/mail/aliases/add -Method Post -Headers $header -Body $parambody
    write-output $AliasResponse
}