Message rejected by the mail handler causes the project pcounter to be increased, but no issue is created

If a mail handler to create issues via email is set up, and the default reporter of the mail handler doesn't have permission to create an issue, the message gets rejected, but the pcounter for that particular project is increased. This ends up having large gaps between issues keys, and no relevant information is shown to the administrators, except looking at the debug logs.

If the message is rejected, the pcounter shouldn't be updated.