This document gives you a few general recommendations when it comes to upgrading hMailServer from one version to a newer.
Before you upgrade hMailServer, you should back up all your email messages and settings. It's very rare that an upgrade of hMailServer fails, but if it does, you might need to restore a backup of your installation. Remember that if an upgrade fails, all your email may be lost so this is very important that you backup your system before upgrading.
Generally, there's no need to uninstall the old hMailServer version before installing the new one. The hMailServer installation program will automatically stop the current hMailServer installation before installing the new version. The recommendation is therefore not to uninstall the existing version before installing the new one.
The exception to this rule is if you upgrade from hMailServer 3.x to hMailServer 4.x. The hMailServer COM API has a new name in hMailServer 4.x. If you don't uninstall hMailServer 3.x before installing hMailServer 4.x, these old API will still exist on your system. This should never cause any problems. But if you don't want the old API to still be available, you should uninstall hMailServer 3.x before installing hMailServer 4.x.
Uninstalling hMailServer does not remove any email messages, accounts or other settings. You can uninstall hMailServer and then install it again without losing any messages.
The below steps are the same for most hMailServer version. For version specific informtion, plese see the Upgrading topic in the documentation.
When upgrading hMailServer to the latest version, you can install the latest version immediately in step 3. For example, when upgrading from 4.0 to 4.4, you do not have to install 4.1, 4.2 or 4.3 since version 4.4 contains all changes made for 4.1, 4.2 and 4.3. It's possible to upgrade directly from 2.0 and later versions to the latest version without installing any other versions inbetween. There are exceptions to this rule though:
Is my data preserved when I upgrade?
When you upgrade from one version to a later version, the data in your database and all email messages are preserved. However, there's a risk that something goes wrong during the upgrade so it is still important to take a full backup of your installation.
Will hMailServer continue using my current database?
When you upgrade from one version to a later version, hMailServer will continue using the same database as before. The upgrade process will update the database table structure so that it is compatible with the new version of hMailServer.