Setting up inbound emails

We are developing the use of our Citizens Portal and need to enable inbound emails and I have some questions.

Should the inbound handler be set up in Central or on the host where the outbound emails are sent from?

Our outbound emails use our own domain name rather than the default, at the moment they go from, and we want to be sure the inbound will work with our domain for customer replies. Do other people do this? How easy is it to set up?

We’ll be changing our outbound emails to be sent from, what would our IT department need to do to direct emails to this address into the LC environment?

Any assistance on inbound emails will be appreciated.