1 and 2 should both be correct.

In general if you need to support multiple versions of Outlook with one
codebase you develop with the oldest version of Outlook you need to support
and don't use features of later versions. Of course with the new ribbon that
breaks the old complete compatibility unless you can live with your addin
buttons for Inspectors being relegated to the Addins tab.

--
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Absolute Beginner's Guide to Microsoft Office Outlook 2003
Reminder Manager, Extended Reminders, Attachment Options
http://www.slovaktech.com/products.htm


"abcomp" wrote in message
...
Hi,

I've been reading a lot about the VSTO and have developed some sample
add-ins for Outlook 2003 and more recently Outlook 2007 beta 2. What I
havn't seen is how interoperable my add-in will be between different
versions of Outlook. Are the following statement true?

1. My VSTO Add-in developed with Outlook 2003 will work with Outlook 2007

2. My VSTO Add-in developed with Outlook 2007 will work with Outlook 2003.

For both of the above I'm thinking about just the core events common to
both versions of Outlook (I realise that events specific to a version of
Outlook will only fire in that version of Outlook). I'd like to develop a
single Add-in that can support both versions of Outlook using the VSTO and
C#.

My predicament is that for a new project we are having to initially use
Outlook 2003 with a view to upgrading to Outlook 2007 in the future. Do I
start developing with Outlook 2007, but only handle events fired by
Outlook 2003 (Outlook 2007 should be released by the time this project
goes live) or do I stick with 2003 and treat 2007 as an upgrade project in
the future?


Thanks

Alan