Use this condolence letter to express sympathies for a deceased friend, even if you don't know the recipient.
Dear {Recipient},
You don't know me, but I knew {the deceased} through {however you knew the deceased}. I was very sorry to hear about {his/her} passing, and I wanted to extend my condolences.
{The deceased} was {adjectives you would use to describe the person}, and I am truly sorry {he/she} will not be around any longer for {something you did with the deceased}. But I am trying to rely on my memories and my knowledge that those {the deceased} loved and cared for are strong and will make it through this tough time.
Please let me know if there is anything I can do for you or your family.
Sincerely,
{Sender}