Routing table modification for applications to use specified network interface, based on domain name

Hi!

Apologies if this is basic stuff, I do not have any expertise in networking.

I am looking for a way to edit/modify routing tables (preferably via an app and without needing to use Terminal), and to specify routing based on domain names as opposed to IP addresses.

The problem I am trying to solve is being simultaneously connected to ethernet and wifi, with 99% of traffic going through ethernet and only connections to mail servers going through wifi (all outgoing mail access is blocked on my network - incoming is not - don't ask . . . ).

I can achieve what I want just by plugging / unplugging ethernet and toggling proxy settings but it seriously disrupts workflow and is not ideal.

So any advice on how one can set a routing rule based on domain name as opposed to IP address (preferably via an app - but happy to try Terminal if not too convoluted) would be much appreciated.

I would ideally be looking for something simple like the below example, except with the ability to do domains as destination instead of IP.

Any help would be greatly appreciated.