Why NC Drill as .txt instead of .drl?? how do I change?

Eagle generates drill file as .drl

Every fab house I have used (7 different ones) have accepted this without problem.

Why does Seeed require a .txt file? How do I convert .drl to .txt? Is it as simple as changing the file extension?

received a reply that they will accept .drl files so it is not a problem.

You could have just renamed to .txt