Seems as if Magento has a problem with the email address. Did you enter a valid and syntactical correct email address in the installer during installation? You can probably fix that by setting the email address manually in Magento.
The APS packages configure the fields that they need dynamically in the installer. Ok, then this might be the reason for the problem. The packages are from apsstandard.org and not ISPConfig, maybe there is an issue in the package or it's just an incompatibility.
It can be a problem with an incompatibility of that package with the APS installer in ISPConfig or a problem of the package itself. Either you try to find out where this email address is stored in magento (might be a config file or the database) and set it there or you install magento the traditional way into the website directory instead of using the aps installer.
