encryption - Program to encrypt a file so that it is safe to email

I need to be able to email a very sensitive file. I don't want any one without a password to be able to see anything in it.

Is there a free program out there that will do a really good encryption based on a password and then let me email it and pass on the password (by voice) so that it can be decrypted on the other side?

Answer

Use 7-Zip to encrypt into a zip file, using AES encryption, and you're all set.