Defaults to your incoming email address. All other instructions are ignored. The open command is mandatory. Only cs.arizona.edu can be accessed from this server, but it must be specified as the site to log in as any user other than anonymous. User and password can be specified for users with accounts on cs.arizona.edu.
Defaults are cs.arizona.edu, anonymous, reply-to address.
These are mutually exclusive options for converting a binary file before emailing. There is no default. Defaults to binary. As this is a binary file it has to be transferred in binary mode. Although compressing ls output makes it binary, which then has to be encoded, it still ends up smaller than the original.