I have just started working for a small manufacture which has its own email server (Ubuntu 9). This system has worked well for them for years but has started having problems with spam. I looked into upgrading and it appears that just creating a new email server is the way to go. I have gone through several tutorials and installed the server software multiple times and on the weekend and late evenings taken the old server down and put the new server online to test and as might be expected have had problems. What I would like to do is find a way to leave the production email server running and put the test server up at the same time to fully test and get it working and then place it into production. Could anyone point me to some documentation or article which would explain how to setup the dual environments?
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