Electronic post (1-4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">electronic post</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for e-mail that I've seen before include "Means of communication" , "Electronic post" , "Send a message" , "Online correspondence" , "Online message" .)