The ForeFlight expected route emails are generated via a connection to the FAA SWIM feed. So, ForeFlight passes on whatever it gets back from the FAA through the SWIM feed. In some cases, there will not be an expected route issued at all. In others, the expected route wonít be issued until just prior to departure. But in many cases, the SWIM feed immediately provides an expected route, because the HOST computer is able to issue one.
On that one, I ended up filing on the fly with an Atlanta Center controller while idling on the ramp.
I am not sure what is meant by this. Are you saying that you filed via ForeFlight, but when you called for clearance, one was not available?
Regardless of whether you get an expected route email, your flight plan will/should be on file.