The option, Reprocess failing emails, is available on the Advanced tab of the ReadSoft Collector General settings dialog. It makes it possible to handle emails that fail in different ways.
Occasionally, errors can occur that may cause the program to crash or loop indefinitely (when run as a service, for example, the program may try to restart if the processing of a large invoice results in a response time that is too long). If the same input source is used again, Reprocess failing emails can be deselected in the configuration to move the failing email to the Error folder and log it as an error instead.