We have a customer which uses a form for Outlook written by another company
in 16bit VC++. This old form can still be used in Outlook. We need to change
some things and re-write the form for 32bit. The old form has a .cfg file,
an .EXE and two icons (different sizes). The old form is practically only a
template to write mails in a standard way (mandatory subject line, mandatory
custom message type selected from a list, etc.). Our new form should replace
the old form. When viewing messages created with the old form and the new
form is installed, then they must display correctly with the new form, so we
can only increment the version number. The old form has a custom message
class similar to IPM.INTERPOL.AlertMessage. The new form must work on
Outlook 2000 and Outlook XP. On the internet I only found information about
how to customize existing forms graphically.
Questions:
- Where do I find information about how to write code for this and object
models, etc.? Can you provide any internet links or know of an SDK?
- In what language should we write it? VBA? C#.NET? What would you
recommend?
- General recommendations?

Eric