A user was annoyed with Outlook because he couldn't create a rule to BCC himself on messages.
How do I create a rule to BCC myself? I like to keep my replies in the
folder where I file the customer's messages and thought it would be easier to do if I BCC myself. I want the messages in the customer's folders because it's easier to find the sent messages there instead of in my unorganized Sent Items folder.
Outlook doesn't have a rule to add a BCC when you send message, but you can use a utility or a macro to always BCC an address. However, you may not need to use BCC. If you file the customer's messages before you reply, use Outlook's option to save sent items with the original when the original is not stored in the Inbox. This option is in File, Options, Mail. Look for the option to save replies with the original message about halfway down the page.
If you have Outlook 2010 or newer, Outlook's Conversation View will include Sent items (and messages from other folders). Look on the View tab for Show as Conversation option to enable Conversation view. Show messages from other folders is in Conversation Settings.
If you really want to BCC the messages, I have a macro at
Automatically BCC All Messages. That page also contains a list of utilities that can BCC messages you send.