...
The easiest way to send files as encrypted zip files is through a software service. You can download the software, use it to encrypt the files you need to send, and then email it to a recipient. To communicate the password to the recipient, it is recommended that you call them or tell them in person-- do not send the password via email. That email can be forwarded and if you include the password in the same email as the file, the encryption will no longer be useful.
For more technical users, other methods of encrypting zip files include using SFTP, SCP, or other encrypted file transfer protocols. It is also possible to encrypt zip files using SSH and netcat.
What follows is an example workflow for downloading and using a zip file encryption software. In this example, we will use 7zip, a free and open source software.
...