A landlord reference letter is used to confirm that a person has been renting from you.
If the letter is being sent as a hard copy, then it should be in the proper business format, otherwise, if the letter is being emailed, it should have an appropriate subject line and proper grammar.
I am the property manager Tree Top Apartments. Mr. Jones has been a tenant of my apartment building at 509 Vineyard Ave Unit 12 in Trenton, NJ since May 21, 2017. Mr. Jones is current with his rent payments.
If you have any further questions or concerns, do not hesitate to call my office at (999) 999-999 between 8am and 6pm Monday through Friday.