Recently I did a test install of Exchange 2016 and ran into a few problems which drove me mad for a while as the issues and symptoms did not give any clue as to how they were eventually resolved!
I did a fresh install on a stand alone Hyper-V Virtual Server with 4000 GB of static RAM, 4 processor cores and a 40GB VHD.
Microsoft recommends a minimum of 8GB for mailbox role, (see here) but I couldn’t believe it would actually need this much on a test Server, and I’ve always used way less than the recommended for initial test installs as they will be under no stress at all.
The install seemed to go fine, all the prerequestites were installed by the downloaded media, and the server restarted. On trying the open the webpanel I was continually told that there was a memory error, and to try again later. I ramped up the RAM 1GB at a time but I couldn’t login to the panel until the Server had the full 8GB assigned.
After creating my first test mailbox whenever I tried to send an email I received the below error:
“You don’t have permission”? WTF after going round and round in circles looking at users permissions believing that I needed to assign user permissions I found an obscure forum post which pointed me in the right direction. The solution was to remove the secondary DNS entry from the Exchange Servers network adapter! After removing this and then restarting the server the error disappeared.
I was now able to login and send emails internally and externally, however I was not able to receive emails either internal or external. I wasn’t getting any bouncebacks which could have given me some information on what was going on, I double checked my external DNS and MX records but all were correct.
In the end I used the Microsoft Connectivity Tool and this pointed out my issue immediately, and the issue was disk space. Even though the Exchange server had only 1 mailbox and nothing else installed, 40GB wasn’t enough! I checked disk space and there was plenty of room, but after digging a bit deeper it turns out that Exchange needs a percentage of free disk space and so the VHD had to be expanded. Once this was increased I finally had a working Exchange Server. Hope this helps out someone else as this drove me crazy for a few hours and the errors were not pointing me in the right direction.