I've had an issue with Comcast blocking my server's IP's for months.  It's not blocked in their official blacklist and dozens of calls and hours of work have not managed to put me in touch with anyone at Comcast who can help, but it's only blocking a chunk of my IP space and I've lost several clients.  We had one single hijacked account that was quickly resolved before this started and they seem to have blocked us out of their normal mechanisms for which there is no tool to request delisting from and zero people to contact besides their general tech support number which of course reaches people overseas who don't understand postmaster issues.

So I need to forward any email that is sent by my customers or forwarded to comcast.net addresses to a different server.  I have another server that will work, but I'm wondering how to configure this on the primary server so that comcast.net email, or for that matter any failed connections, get forwarded to this other server for delivery.  Does that functionality exist?