I think you're referring to the msgbox that pops up and says: "A
program is trying to access e-mail addresses you have stored in
Outlook." I get that when trying to do mail  merge with Excel/Word
and using Outlook to send  emails.
There is no direct way to disable this feature; if you have Outlook
2000 or higher it may be installed and turned on by default. If you
are using Outlook with an Exchange server, your network
administrator would have to turn off the feature. This would
compromise security should your system acquire any viruses. There
are some ways to code around it and you can also send email other
ways, but I'm not really sure how it works.

There are programs that claim to bypass this or assist in
automating, ClickYes is one of them. Check it out here:

http://www.contextmagic.com/express-clickyes/