I am looking for an open-source / free SMTP server that will enable me to automatically change the content of outbound messages via a simple search & replace (or regular expression). It should be able to be configured to do this only for emails being sent to addresses that match certain domains.
Specifically, I have an application that sends emails containing URLs. I need to be able to be able to perform a search & replace on those URLs before the email is delivered. I cannot change the application itself, but can point it at an SMTP server of my choice.