The customary way to handle validation for Outlook items would in the code behind the custom form.
Creating and updating items is done with the Outlook object model.
FYI, there is a newsgroup specifically for Outlook forms issues "down the hall" at microsoft.public.outlook.program_forms or, via web interface, at http://www.microsoft.com/office/community/en-us/default.mspx?dg=microsoft.public
.outlook.program_forms

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> I'm trying to find an ODBC to connect to outlook's database, and I dont
> know where to start from.
[quoted text clipped - 7 lines]
>
> ~Rama
~Rama - 16 May 2006 02:18 GMT
Thanks a lot Sue! I checked that microsoft link, its very beneficial.In
addition, I've been into your outlookcode.com several times every day
to try to understand outlook ODBC first then move forward to the next
step with my project. But since i'm just a beginner, and having a hard
time getting a head start, or understand where does outlook's database
reside and how do I ODBC to it. are you aware of a link that guides me
a step by step method?
I greatly appreciate your support.
Sue Mosher [MVP-Outlook] - 16 May 2006 13:11 GMT
There is no "Outlook ODBC" per se. While it is possible to access Outlook folders through OLE DB (see http://www.codeproject.com/database/connectionstrings.asp#OLE%20DB%20Jet and http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsmart00/html/
sa00h12.asp), that technique will not expose all the properties and objects that you are likely to want to work with to create new items using custom forms. You should use direct Outlook automation methods instead.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> Thanks a lot Sue! I checked that microsoft link, its very beneficial.In
> addition, I've been into your outlookcode.com several times every day
[quoted text clipped - 5 lines]
>
> I greatly appreciate your support.