Exchange won’t apply delete rule action

We have a Microsoft Exchange Server 2003 SP2 (v6.5.7638.1) for some user accounts. For one of them I've created the following Outlook 2010 rule to automatically delete mails from a certain origin:


Apply this rule after the message arrives
from deleteme@example.com
and sent to mailbox@example.net
forward it to myself@example.net as an attachment
and delete it
and stop processing more rules


So I want mails from deleteme@example.com to mailbox@example.net to be deleted. For debugging purpose, I'm also forwarding matching emails to myself.

Now the issue is that mails are being forwarded to myself (so the rule is working) but they are not being deleted.

I've enabled maximum logging for rule actions at the Exchange level and I can see that the rule is triggered:


Triggering the rule (Delete from deleteme@example.com) with sequence number 10.
The distinguished name of the owning mailbox is Mailbox.
Database "_Company\_Store1".


So the rule is triggered but I can't see why the mail is not being deleted. All I can see is that the message is being delivered (what I don't want).


Message was successfully delivered to <MSGID-deleteme@example.com> on /o=Company/ou=Mailboxes/cn=Mailbox.
Internet Msg Id:_Company\_Store1.


Note that I've got another rule to delete emails with the same issue. Any idea why the emails are not being deleted?