I need all outgoing emails to go to one account

I have what seems like unique situation. Maybe it is not. I have looked on this forum and googled. I have absolutely no idea where to start or if it is possible. Here it goes.

I need every bit of outbound email to go to a specific email address. I have a site with multiple users who will install plugins etc… and they if they use gmail and yahoo addresses they do not get their requests. I have a non-free email account that doesn’t do all the funky stuff the free ones tend to do with form requests. Even if a new plugin is installed and the person inputs their email address it still sends a copy to the paid account.