$svc = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$col = New-Object -TypeName Microsoft.SharePoint.SPAlertTemplateCollection -ArgumentList $svc
foreach($a in $col)
{
    if ($a.Properties["Custom"] -eq $null)
    {
        continue
    }

    Write-Host "======================================================================="
    Write-Host $a.Properties["FriendlyName"]
    if (![System.String]::IsNullOrEmpty($a.Properties["NotificationMessage"]))
    {
        $s = $a.Properties["NotificationMessage"]
        $s = $s.Replace("http://www.taloyhtio.info/unohtuikokayttajatunnus", "https://www.osuria.com/unohtuikokayttajatunnus")        
        $a.Properties["NotificationMessage"] = $s
        $a.Update()
    }
}