Short Sympathy Is It Ok To Write A Short Sympathy Note By Email?

Is it ok to write a short sympathy note by email? - short sympathy

The father of my friend just died, I am me and my friend from Europe and his family in the United States. Is it appropriate to write a note of condolence e-mail? A note in the mail takes about 4 days to get there, and I your email address.
I intend to appeal, but they said they are very busy, takes care of the funeral, etc. .. What should I do? Thank you to everyone