I had to quickly migrate 300 email users and their varied domains to a test ISPConfig 3.2.5 server yesterday that I had already set up. The old server (and therefore all the clients in the field) were configured to use ports 110 and 587, no SSL (it was an OLD server). 587 was used as the workaround for ISPs that were blocking port 25 usage as a way of preventing spam proliferation. Annoyingly, as I got email users recreated and mail started flowing, I didn't notice that clients weren't able to send. For the sake of compatibility, it would be nice if the Perfect Server instructions included a reference to uncommentating 1 line in master.cf to enable port 587 usage, or have it enabled by default. After fielding a few complaints about not being able to send, and finally realizing I was having to change the port numbers in Outlook to get it to work, I found the fix on the server, reloaded Postfix, and the phone calls stopped. If there's an argument that needed to back up the suggestion, it's backward compatible. If the argument is "you should be using SSL" (I agree), then at least a reference to how to enable it in the instructions would be nice, just as a reminder for those that don't have to think about that type of thing that often. In my case, it was necessary to get the server operational ASAP, without a lot of client fiddling - I can implement SSL certs and move them to that when the crunch is over. As it turned out, ISPConfig stepped up and filled the void pretty well - there were some OS deficiencies, but that I can overcome with a newer OS/server when things settle down.