Some email servers remove images from email body. This will cause PayPal image as well as the invoice link to your invoice be removed.
Although it is an inconvenience that you cannot make payment by a simply click from email, because your invoice itself is still in your billing account, you can still find it there.
Just go to billing.angelspeech.com, login to your account using the same email (and same password if you have not modified it) as your scheduler.
The first page after your login shows your Payment stats. On Invoice Stats –> Total Due–> Click the number in the bracket. This will display a list of your invoices. Click on the invoice number (usually it is the only one listed) to open the invoice. If the invoice is not paid you should see the PayPal button image “Pay Now” on top right.
Click the “Pay Now” button to make the payment in PayPal. Your Payment will be automatically applied to your account to either create your account (if you are paying for a new service order) or renew your next month’s service.