Although a binary file cannot be inserted in a mail message, mail programs can now encode a binary file and then attach it to a message. So by using an attachment, you can e-mail a binary file in its original form to a colleague. When the message reaches its destination, the mail program used by your recipient should be able to detach the encoded file, decode it into its original form, and create a copy of the binary file on disk. If all works correctly, neither you nor the recipient will see the encoded attachment - only the original file. Any special character can be represented by a simple text code.
Mail programs use such a technique to create attachments, using established coding systems.
For historical reasons, three encoding systems are used by e-mail programs. Most mailers can handle at least two of these systems. All email programs are now normally configured to use MIME as their normal method of encoding. Unix has the uuencode system,also adopted in the PC world. Apple computers use the BinHex system.