Pattern
The pattern field is for entering the identifying information that will enable the filter to correctly identify the email messages.
• If the type is IP/Netmask the filter will be an IP address with a subnet mask.
• If the type is Email Wildcard the filter will be an email address with a wildcard symbol in place of the variable characters. For example *.example.com or fred@*.com.
• If the type is Email Regular Expression, regular expression can be used to create a more granular filter for email addresses. For example, ^[_a-z0-9-]+(\.[_a-z0-9-]+)*@(example|xmple|examp).(com|org|net) could be used filter based on a number of combinations of email domain names.