E-mail option is a term used to describe the various options available when sending or replying to an email. The most common options are REPLY, SEND, and ReplyAll. REPLY is a 5 letter word that allows the sender to respond to the original message. SEND is a 4 letter word that allows the sender to SEND a new message. ReplyAll is an 8 letter word that allows the sender to respond to all recipients of the original message.