Hello from JustAnswer!
Are you paying bills in one country or multiple countries?
It appears you are offline, so I'll leave some information.
You might try the online bill pay services at the following money transfer websites:
Depending on the money transfer company, you can pay directly to the biller online or have payment delivered to their address.
The world has countless ways to send money. What I am asking about is a way to send mailed money orders through online payment. The websites you mentioned do not offer this service. The closest thing is "cash delivery" from xoom.com which would not work for my purposes.
I have been on ebay for a long time and I know that a company used to offer this service, perhaps it was even Western Union, but I don't think they still do.
If I am mistaken, I would appreciate if you could show me where any of those websites offer what I am asking for.