I setup my own postfix server, etc... I use imap for bounce handling. Unsubscribe email I haven't had to do anything with. They click the link and unsubscribe, and it doesn't sent to them anymore, along with the fact that I can filter them out of my segments for an accurate count.
You need a pop or imap to have a bounce email address that doesn't have an issue with Mautic appending to the bounce email address. You would probably have to use a catchall or something if you were using cPanel. I don't use cPanel, etc... I use a custom setup mail server where my Mautic install is on a subdomain on a different server then my mail server.
As far as FBL emails... I have to manually manage those. I have seen no way to manage those in Mautic, and those are pretty important if you are mailing to large lists. I am probably going to have to write something to manage that.
Hopefully you get it figured out...
As far as my problem with contacts that are manually set to "Do Not Contact" I think I am just out of luck on that one, unless I write something somehow for that as well.
The reason I have to manually add them to DNC is because of the FBL issues I just mentioned.