Spam elimination by visual pattern recognizion
I'm getting so much junk mail that the sheer amount actually eases recognizing it. Thunderbird does a wonderful job in placing the spam messages into it's Junk folder, but although it never has done a false positive (determining that a non-spam email is spam), I do not trust it completely and want to glance through the junk mail titles before actually deleting them.
When the amount of received spam is huge, I know that a group of emails is spam if the pattern formed by the letters of the subject is repeated in the screen and I do not need to read the titles, which makes ensuring the spamness of the emails very easy. Of course, there are some junk mail messages with unique subjects, which don't form a pattern, but these are a minority. It is possible to determine from the screenshot with it's size scaled down, which emails are spam even though the letters are not readable.
This method will fail if someone sends me repeatedly messages with the same subject and Thunderbird makes a false positive, but the odds of that are quite small and besides such a behavior is quite unusual so I don't care.