Stressing that this is a violation of integrity that won't be tolerated will likely cut down on such behavior.
Preventing the “corrupted file” trick
Tag: corrupted file
If … there be kindness I can show, or any good thing I can do to any fellow being, let me do it now, and not defer or neglect it, as I shall not pass this way again. ~ Etienne Grellet
Stressing that this is a violation of integrity that won't be tolerated will likely cut down on such behavior.