Basically, Would be really great that after installing ISPconfig in business environment we can use it to switch mail server from external (existing) to internal (in-house ISPconfig). I have a few clients who have over 80% of their mail sent/received within organization and it would be great if I could place ISPconfig in their local network primarily to handle mails. Of course, that wouldn't be its soul purpose, ISPconfig would serve their web applications as well but while employees are within the organizations local network, e-mails would not go to the external mail server and back to the other empoyee (if they are sending e-mails to each other) - instead, e-mails would go to ISPconfig and straight to the receiver (other employee) BUT ISPconfig and existing (now only) mail server would sync so that when employees are not within the organizations local network (home, business trip...) and (for instance) organization Internet connection is down - they would still be able to send/receive mail (and when ISPconfig's Internet connection is back on, it would re-sync with the "secondary" mail server (the external)). I hope I'm making any sense
So, To answer my own post For anyone interested, I found that this is the solution: https://www.howtoforge.com/communit...il-on-ispconfig-3-debian-7.68686/#post-326314
