I had myself this problem and I decided to find out how to fix this issue since it was driving me crazy. Hope this saves you time.

Explanation

Everytime you send an email from your BlackBerry or your gmail, a copy of that email arrives back to your BlackBerry inbox as email sent. All this comes because when you send an email is saved in the Sent Items folder (Gmail or other client you use) and BlackBerry instead of knowing is a sent email marks it as new.

How to fix it

First off you need to open your BlackBerry Internet Service portal with the service company you are using. Login and create a new filter.

In the image above we called the filter name Block Sent Items. We applied filter from field and we chose the emails this will apply to.

The most important part is to check where it says “Do not forward messages to device” and click Save. Exist the Blackberry Service website and your own emails won’t be reaching your blackberry ever again.

If you are on Microsoft Exchange server, you may disable the synchronization of Sent Items folders (that contains your emails sent from the Exchange mailbox) via BlackBerry itself.