Konica BizHub 7145 Scan to Email issues

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Certain documents seems to give us trouble when scanning to email. On some occasions, the scans will send just fine. On others, we get this:

"JSzrSEREREREREMEkwSSWkECpoIIhEFI6Zh0IkfCTKHC2UOUO CSOphKyOiPEdBBYkeCCxI6B
FDhCR0ghJjEILEj6QkhENMqccjEEENkdJCkkkyhwhEIIREXiIi IiIiIiIiIiIj4iIiI4jiws
WUOEJLoECojoEFiJHwkSpEfI+R0R8jojo0RdEfI6I6CC8hEXRH RHRdCR0CBJCyvpJEdFOs1I [...]"

The image is just a plain sheet with text on it. Why does this happen?

EDIT: I lowered the resolution from 300 DPI to 200 DPI and it worked. But why? Why does that work for some documents?