Over on https://github.com/pazz/alot/issues/1449, a user asks:

>  I would like to query for `mailcount`, for example
>  to search for mails on a mailing list which got answered 
>  `:search tag:list/questions and mailcount>1`
>  or
>  `:search tag:list/questions and not mailcount:1`

This seems like a question for notmuch (and maybe for xapian).  I don't
know how to do it off the top of my head.  Any takers?

        --dkg