Overpass query: add my mail address?

I have a vague memory of a recommendation to include my mail address with overpass requests, so that the admins can get in touch if annoyed, or with suggestions for improvement. But how to do that? Suppose a little script like below, where and how to add $MY_MAIL_ADDRESS?

 <query type="node">
  <has-kv k="shop" v="supermarket"/>
  <bbox-query w="6.0" e="20.0" s="50.0" n="60.0" />

Or is it an addition to the wget command that transmits this request to overpass? I now have something like

wget -O $XMLFILE -o /dev/null --no-verbose --postfile=$POSTFIL http://overpass-api.de/api/interpreter

PS I was unsure under which chapter to post this - @admins, feel free to move/shuffle!

I have no result when searching for mail or email in the OSM wiki about


or its sub pages.