Yes, every unread message is process through the filter set but since the second rule you showed me is the last rule then each unread message is processed through two rules.  Consider ending your rule set with an Always Exit rule.  In your case you would replace your  'Expression *" rule with an Always Exit rule,

 Also,  expression rules are much slower to process that header rules because they check the entire message contents rather than just the headers.  Replace your "Expression *.biz" rule with a header rule that checks the From header for ".biz" (no quotes, no wildcards).   This should accomplish what you want but process much faster.

I have to state that I would be very wary about doing what you are doing unless I was certain I never wanted to receive a message containing .biz or .biz in the From header.  If there is the slightest bit of uncertainty, set the action of you rule to move the messages to a designated folder.  You can then review and delete them at your leisure but at least you will have an opportunity to see them.

I am unable to filter out a particular domain extension.  By this I mean that I want to filter out all incoming mail from a particular country or extension type.  For example, let's say that I want to remove every email with a ".biz" extension.  If I create a filtering rule to Delete all .biz emails by typing in ".biz" in the "Contains this text:" box, those emails are NOT deleted!  Is there some syntax that I don't know about?

Are you using a new mail filtering rule?  If so, be advised that only unread messages are processed through the filter.

Yes, I realize that we're talking ONLY about unread messages.

 My problem is that there seems to be no wildcard character like "*" that can be used in a filter.  I am trying to delete, in my example above, all messages from *.biz.  The problem is that some .biz messages stay in my New Mail box regardless of my filter, which says (again, this is an example) ".biz" in the "Contains this text:" box.  In other words, these messages do not get filtered out.  They have NOT been read when this happens.

The help file has information about the difference between a Header rule type and an Expression rule type including the use of wildcards in Expression rules.  In your case, detecting .biz in the From header should work.  Tthe first thing to do is to

rule out a problem with rule logic.  To do this, place your rule as the first

rule in the rule set.  Make the second rule an always exit rule to insure no other rules are processed.  Now close

then reopen the new mail folder and see if it works.  During troubleshooting consider

changing the action of the rule to set the message color.  This is a safe way of determining whether a rule is being triggered.

Thanks for this tip on using Expressions in mail filtering rules.  I had actually never read this part of the Help, and it seems to pertain EXACTLY to what I'm trying to do.  Your troubleshooting tips will also be helpful in making sure my rules work as expected.  So far I have gotten partway there, and will check back if I get stumped.

Thanks again for your help.  This is exactly why I wrote to the forum!

 Lance

OK, I really AM confused.  In my new mail filtering rules (used when the folder is opened) I set the first line as

Expression *.biz  Delete

and the second as

Expression *   Exit this rule set

My rules all still execute.  Why?  I expected to see just a couple of seconds to elapse while the one message (unread) that matches the first criterion is moved to Deleted Mail and

then the execution would stop.  I see the "Applying filtering rules..." message for, say, a full minute before the New Mail folder opens.

What the heck is going on?  I'd think that ANY message would cause the execution to end at the second of these rules.

[quote user="LanceG"]What the heck is going on?  I'd think that ANY message would cause the execution to end at the second of these rules.[/quote]

It doesn't work that way.  Every unread message gets processed through the new mail filter set.  Consider the intent of you rule, to delete all new messages from *.biz.  Each new messages must be processed through the new mail filter rule set in order to do that.

[quote user="bfluet"]It doesn't work that way.  Every unread message gets processed through the new mail filter set.
[/quote]

Yes, but my two new rules are now the first two lines of my new mail filter set, so even though I have a lot of unread messages, it shouldn't take long to run them all through those two rules.  Do my rules themselves look OK?  I thought that my second line would cause each unread message to "exit the current rule set" and thus skip all of the other rules in my set.

 Maybe I said it incorrectly in my previous mail.  I meant that any UNREAD message should exit after the second rule.  Is that correct?