• Rework packaging.
• Improve CURL request error handling.
• Use config file path from package installation path.

Note: If chroot-jailing is enabled in Postfix, SSL/TLS root certificates may not end up in the right location within the chroot, resulting in SSL-related error messages. The easy fix is to disable chroot jailing for Postfix. The harder fix is to manually copy the certificate files to the right locations.