升级到SP3后，操作outlook,比如新邮件等就会出现如下提示：
Don't panic. This is the "enhanced" security model of Outlook 2000 (SR2 and newer), Outlook 2002 and Outlook 2003. There are some ways to stop these annoying messages. And the simplest one is to download and install Express ClickYes, a tiny freeware utility that will click the Yes button on your behalf.
Express ClickYes v1.1 is compatible with:
- Outlook 2003
- Outlook 2002 (SP1, SP2 and SP3)
- Outlook 2000 (SP1+SR1, SP2, SP3)
Express ClickYes accurately defines Microsoft Outlook's security prompts and clicks the Yes button only for these dialog boxes. It doesn't affect any other windows having Yes buttons.
ClickYes doesn't work with Outlook Express. There is an appropriate option in the Outlook's Express settings. To turn the prompts off, click Options on the menu, switch to the Security tab, and clear the Warn me when other applications try to send mail as me checkbox. For additional information, look at the screenshot below.
参见：http://www.contextmagic.com/express-clickyes/
最简单有效的办法是修改注册表：
HKEY_LOCAL_MACHINE\Software\Microsoft\Office\Outlook\Addins\PDFMOutlook.PDFMOutlook\
Change LoadBehavior from 3 to 0
参见：http://www.experts-exchange.com/Applications/MS_Office/Outlook/Q_20652766.html