Alternatively, you can send a plain note. This is especially appropriate if you feel you have a lot to say. However, if you’re at a loss for words, stick with a store-bought card, as they don’t lend themselves to a lot of writing. While muted cards are “normal” and socially acceptable, consider using blank cards that reflect the personality of the person whose life is being remembered. For example, tasteful images of a motorbike for someone who loved riding. Do not email a sympathy thank-you. Though this is the most convenient way to contact people, it is also extremely impersonal and will be considered a serious faux pas.
There is no need to add their title. For example, you should write Dear Dr. Brown instead of dear Brown MD.
If you can’t think of something nice to say about the recipient(s), compliment the present/gesture instead. For example, say that gift comforted you at a dark time, that the flowers were the deceased’s favorite, etc.