Search and graph deleted tickets?

Here at the University of Oslo, we try to move all spam messages into
a dedicated queue (spam-suspects), and set the status to deleted.
This hides all spam messages from normal searches, and make sure we
have them contained in one place only visible for those reviewing
potential spam before setting status to deleted (And thus unclutter
the view for all others).

But, I would like to know how many spam messages arrive, and thus want
to search out all deleted tickets in the spam-suspects queue, and then
draw a chart on the number of created tickets per week or month. Is
this possible? As far as I can see, there is no search-flag available
on the web page to be able to find deleted messages.

I’ve found the flag to make it possible to search for deleted tickets,
but I am unable to find a way to set this flag using the web search

What is the best way to implement this feature?

I probably want some checkbox-like feature, ‘[ ] include deleted
tickets’ or something like that.

Petter Reinholdtsen