sophj - as you can see we are unable to agree on this so I suggest if this is a business letter, and you have a phone number, a quick call to the offices of the person concerned would be useful. I'm sure the receptionist will enlighten you as to the proper title of your intended recipient. Or, again if it is a business letter, you address it to the organization then put Dear Sirs but add "For the attention of Jane Smith". If it is a private individual as previously said just address them by name which is perfectly acceptable nowadays.