Wildcards are a way to match any combination of words or symbols. The best way to explain wildcards is to show a few examples. Consider the following:
|Block mail from joe at somewhere.com
|Block mail from anyone who's username starts with a J atsomewhere.com
|Block mail from anyone at somewhere.com
|Block mail from anyone at a domain name that has the wordsavetrees in it.
|Block mail from anyone at a government address
|Block mail from anyone at the network of 205.199.212.x
|VERY DANGEROUS. This would block all electronic mail from everyone.
Wildcards can be used anywhere inside email addresses, domain names or IP addresses. Wildcards can only be used at the beginning or end of subject, message content or header matches.