Re: What is the E-mail filter?

E-Mail filter is a blocking feature that some servers or e-mail programs 
have, it is just a way to tell the program what e-mails you don't want to 
receive. The most basic blocking engine is one where you specify the email 
addresses you don't want to receive that way whenever you get one email it 
will compare against the list and reject or erase the incoming email if it 
is on the list.

This type of program will be on the email server program or on the email 
client program, other variations will block out emails according to some 
rule like all the email addresses that start with john for example or all 
the email addresses that come from @mailserver.com