Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why does FlagStar Bank harass you about payments within grace period?
One option is to try to get a month ahead on your mortgage payments.  Rather than using the current month's rent to pay the current month's mortgage payments, try to use the previous month's rent to pay the current month's mortgage payments.  This should allow you to pay on time rather than late but not unacceptably late.