What are wildcards and why are they useful?
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:
| joe@somewhere.com | Block mail from joe at somewhere.com |
| j*@somewhere.com | Block mail from anyone who's username starts with a J atsomewhere.com |
| *@somewhere.com | Block mail from anyone at somewhere.com |
| *savetrees* | Block mail from anyone at a domain name that has the wordsavetrees in it. |
| *.gov | Block mail from anyone at a government address |
| 205.199.212.* | 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.