Sandbox/catch mails sent from test environment

I'd like to be able to test if my automatically sent mails are really sent, but I do not want these mails to leak to real world. Is there a way to configure my mail settings so that all mails sent from my test environment are automatically forwarded to a single mailbox?

I suppose I can configure addresses in my configuration, but if I replace every e-mail in my system with my test e-mail, I won't be able to clearly check if mails are really created correctly.

While testing, I might enter real world e-mail addresses, but I do not want to risk mails being sent to customers.