Problem in relaying outbound mails for specific smtp
I have this client, and they have a Postfix Email Server, this client wants to make all outbound mails for the domain aol.com to relay on this specific smtp server (an smtp relay server that is located on their backup ISP provider). One problem is that they do not want to relay other outbound mails such as yahoo.com or gmail.com for this smtp.
The reason they want to do this is that Aol does not allow to accept their mails that are comming from our clients postfix server unless it comes from their smtp relay that are located in their backup ISP provider.
Any idea on how to do this?