Sample Notification to Tenant of Late Payment Due on Rent? Certified Letter?

[Jessica F.]

Rent is due on the 1st of the month. The lease allows for a grace period up to the 5th. The lease also states that after the 5th, there is a $25 late fee and after the 10th of the month, there is an additional $25 late fee imposed. The tenant has not paid as of today. It is their first time paying late but I do not want to set a certain level of tolerance for allowing anyone to pay rent late esp with a grace period in tact.

I now need to notify the tenant that rent is past due and there will be $25 fee imposed. What is the best way to notify the tenant of this? Do I have to do it via a certified letter? Are there certain guidelines since the property is located in Philadelphia, Pennsylvania in sending out the notice? Is there certain verbiage that I should use in the letter to the tenant since I have never done this before (any sample letters would be a great help!)?