A binary file can be converted into a text file using the uuencode command. For example:
uuencode source_file file_label > filename
The encoded file has the same ownership and access permissions as the source file. Make sure that you set these to appropriate values before encoding the file and sending it to another user. The name of the file to be encoded is used for the file_label.
You can use the tar command to turn several files into a single file, which is then compressed before being encoded and mailed to another user.