Try to follow this online guide to correctly configure the BullGuard Spamfilter :
https://www.bullguard.com/support/product-guides/bullguard-internet-security-guides/spamfilter.aspx
If this not works, disable the UAC feature in Vista, following this steps :
- Open Control Panel.
- Under User Account and Family settings click on the "Add or remove user account".
- Click on your own user account.
- Under the user account click on the "Go to the main User Account page" link.
- Under "Make changes to your user account" click on the "Change security settings" link.
- In the "Turn on User Account Control (UAC) to make your computer more secure" click to unselect the "Use User Account Control (UAC) to help protect your computer". Click on the Ok button.
- You will be prompted to reboot your computer. Do so when ready.
Afterwards, follow this instructions :
- Open Outlook and go to the Tools menu > Trust Center.
- Go to the left pane and click on the Add-ins option.
- In the Add-ins pane look for the section "Apply Macro Security Settings to Installed Add-ins" section.
- Make sure you choose "Com Add-ins" and then click the "GO" button.
- In the "Com Add-ins" window, locate the BullGuard Spamfilter item, select it and click on the Remove button; after removing the Spamfilter add-in, click on the Add button.
- Browse to the location where BullGuard is installed, select the MailScanAddin.dll file and press the OK button.
(usually C:\Program Files\BullGuard Ltd\BullGuard\Antispam)
- You should see the BullGuard Spamfilter again in the "Com Add-ins" window; make sure it is ticked and press the OK button to close the window and save the settings.