Right-click the Speedster icon
Click Pop-Up Blocker...

Click the White List tab
To prevent pop-ups being blocked from specific web sites, click the Add button, type the domain name you do not want blocked, and press Enter
To remove web sites from the White List, highlight the domain name and click the Remove button
Click the Remove All button to remove all web sites from the White List
Click OK when done

You can also add a web site to your White List by right-clicking anywhere on a page of the web site and clicking "Add to Whitelist".
To remove the web site from the White List, right-click on the web page and click "Remove From Whitelist".