"Since Last Deep Scan - Never?

02.27.19.  I note the phrase "Since last deep scan Never" on my "scan page". Can anybody tell me what it means? There is no obvious icon or other means by which this so-called "deep scan" can be activated.  Ultimate is not doing a good job of scanning my incoming emails.  Two of them, both advertising, cannot be removed to "trash" from my in box.  Over the past few weeks, my two email addresses appear to have been comprimised in some manner.