This is a letter where an employer is giving reference letter to anyone concerned in employing one of its employees. This letter is not written to anyone in particular and hence has no address.
Here is a sample cover letter reference:
The Urban Cooperative Society Bank,
23rd June 2010
To whomsoever it may concern
Mr. Simon Smith has been working with us for the past 5 years. He was found to be a diligent and sincere worker. His character is impeccable. He had worked hard and with responsibility in the various policies related matters. He visualized and conceptualized different projects for the bank.
He was an asset for the bank and will prove one for his future employer also. He will be missed in the brain storming sessions of the banks managerial meetings. The bank wishes him a happy and bright future. May he achieve his dreams and ambitions!
The Urban Cooperative Society Bank