In general, lines you enter on the Email Filters page are assumed to have a blank space on either side. This makes sure that if you enter the word "table", for instance, Email Filters will not match the word "tablecloth". However, there are some cases where you may want to match an unknown piece of information. Say, for instance, you were getting a lot of spam from addresses at spammer.ru. But the addresses weren't always the same. What can you do? Just enter
in your Discard Messages box, and then any messages from firstname.lastname@example.org, email@example.com and firstname.lastname@example.org will all be matched.
Please exercise caution when using "*" as a wildcard, though. The use (or misuse) of wildcards is the top cause of people losing mail.