It would be great to see sending profiles incorporated.
We work with a number of companies that ask us to schedule and send emails for them. We use Postal email server and create a “mail server” for each client, with their own IP of IPs. There are other reasons to have sending profiles as well, for instance, transactional vs bulk.
So either way, it would be great to create sending profiles with user name, company name, server, etc in a profile. This you could choose which profile would be used for emails, campaigns etc.