Multiple Outbound Mailboxes-Define by Agent Group And/Or Customer

Is it possible to define multiple outbound mailboxes? A long time ago with FreshService you could define as many mailboxes (inbound and outbound) as you wanted and define them according to various groups/rules (think divisions, departments, organizations). We are engaging with a customer on a more co-managed scenario and they want to use an internal email for helpdesk tickets and communications (ie, helpdesk@acme.com). I believe I can use email rules (inbound setting) to route tickets on this second mailbox to this customer group, however outbound emails for these customers should also be on this custom mailbox address. It does not seem that we can define multiple outbound emails for the tickets. Anyone have an idea about this? We are engaging more and more in Co-Managed IT relationships and this will be necessary.

I was wondering the same thing.
We were hoping to set up multiple outgoing addresses. Up to now we have just been sending out invoices so we started by adding an invoice@ address.
Currently we are looking into ticket creation and response through our helpdesk@ mailbox but it seems we can only configure the incoming side. The answers would still be coming from our invoice@ address and there does not seem to be a way to add our helpdesk@ as a second outgoing address.
It’s quite strange only a single address can be configured.