If the email requires a reply, press either
<keycap>R
</keycap> or
<keycap>r
</keycap> <command>mail
</command> keys.
<keycap>R
</keycap> instructs
<command>mail
</command> to reply only to the sender of the email, while
<keycap>r
</keycap> replies to all other recipients of the message. These commands can be suffixed with the mail number of the message to reply to. After typing the response, the end of the message should be marked by a single
<keycap>.
</keycap> on its own line. An example can be seen below: