In addition to Ken's ideas, there are some tools and APIs to help synchronize with an existing Outlook store. See
http://www.outlookcode.com/article.aspx?ID=25
"Jean Paul Mertens" <ON7AMI@newsgroups.nospam> wrote in message news:eWnufcmiIHA.2268@TK2MSFTNGP02.phx.gbl...
> Hallo all,
>
> As an Windows forms and Web application developer I was wondering is it is
> posible to use Outlook as an host for my application. I have a own written
> CRM Relation database (in SQL) and I would try to replace the 'Contacts'
> logic in Outlook with our own data and logic so I need a 'folder' pointing
> to my relations-Contacts, a list of my data in the 'explorer' window and an
> 'inspector' where my own form resides for getting and editing the data on my
> SQL database.
>
> I hope this is clear, what I want to do is exchange the default Contact
> folder with my own :-)
>
> Greats,
>
> Jean Paul Mertens
> ON7AMI
>
>