Allows the administrator to block people with a matching e-mail address from posting messages on the forum. It would also prevent people who's e-mail matches the filter, from registering on the forum.
Use this filter if you want to use regular expression masks to match the e-mail address'. This is very useful if you want to block all people from a certain ISP. ex. .*@aol\.com filter would block all people who's e-mail address ends with @aol.com
Internally this function uses preg_match() to evaluate the regular expression.
The regular expression filter can also be used to block all email address', with the exception of those containing some sort of a special string or coming from a particular domain.
Let take this situation for example, you need to setup a forum that would only allow registrations of students and staff of a university. There is a slight complication however, while each student has an email address @university.edu, the staff e-mail address vary between @staff.university.edu and @university.on.ca. Regular expression to the rescue, by using regular expression and FUDforum's special prefix '#' you can easily accomplish this tasks as the example below demonstrates.
Example 1.6.
#.*?@(university\.edu|staff\.university\.edu|university\.on\.ca)$
By entering the code above, you will be able to restrict user registrations to people who's email accounts are on the university.edu, staff.university.edu or university.on.ca domains.