And to make sure all is said,
Email sent by badly created scripts (and spammers) are often missing the "Date:" field. As a result they are considered as being dated of the first of January 1970 (or some stupid date like that) and will be at the start of the sorting.
As roundcube miss the feature to select the index at which email are displayed, I would have to click "next page" around 150 times to be able to drag and drop that mail to the trash.
I can see a few solution to this problem:
bottom right. (I have over 3,000 email in my inbox - and I use folders and filters, so I let you calculate how many time I would have to click "next" to get to a spam email)
Thomas