Thread component (5)
(Other definitions for email that I've seen before include "Digital message" , "Internet-borne communication" , "Message sent via computer" , "Post" , "Electronic message" .)
(Other definitions for post that I've seen before include "Stake, job or mail" , "Maybe letters" , "a placement: it's > part of one's goal" , "Pole - position" , "Put a letter in the box - stop it" .)