The process for transitioning your MTA installation to new hardware is fairly straight forward. Before installing Hurricane MTA on your new machine, you can simply just copy the entire installation directory from the old server to the new one.
It is important to note that you have to use the same exact directory structure. Once you have copied everything over, you can then run the Hurricane MTA installer and configure the server to install into the already created directory.
The only thing you can not transfer directly via file copy to a new machine is the DKIM settings for each account. DKIM key pairs are stored encrypted in the database specific to the physical machine.
There are a few different ways to transfer DKIM key pairs. First, the keys can manually be accessed and copied from one Hurricane MTA Web user interface to the other. Keys that are saved by the MTA in the web UI are stored with the proper encryption in order to be usable by that installation.
If you have too many keys to be transferred one-by-one, the first alternative is that you can use the web services Account.GetSettings and Account.SetSettings methods to programmatically transfer the keys in bulk.
Finally, if you do not need to have both new and old MTA installations active at the same time, there is another work around. Part of the MTA key encryption on disk that is machine specific is the installation ID in the system registry. You could copy this from the old to the new machine. To do this you will need the value from the below registry location on the old machine.
Once you get this value from the old machine you will need to de-authorize the license on the new machine (if its already authorized.) Replace the registry value on the new machine with the old machines value. It will look like a GUID. Once the value is on the new machine you can authorize the license key. The MTA will then be able to load the DKIM keys from your config files.
Unfortunately it is not possible to have two different machines with the same installation ID active at the same time. If you have a requirement to keep them both active then you can't utilize the installation ID transfer method. You'd then have to use web services or manually entry via the UI.