Return-to mail address in system replies

Idea
When corresponding with guests addressing me from my website I wish to have my email address shown, not the long HostAway address, which may be put to JUNK/SPAM folders. This way my guests will know it comes from me.
At the same time, I want the invoice to be sent to another email address, not the general one.
And to top that, I do not want the general email address to be the login credentials.

Problem solved
Guest is assured the email is sent to the business it was intended to.
Invoice is delivered to a specific mailbox, whereas it will not be lost in the "noise" of traffic of the general mailbox.
My login credentials are less obvious, thus harder to hack. 

Currently
I need to copy the guest's address to my mail application and the body of the mail, too. Then answer from my mail app, rather from the system (though we started to use the system, lately)