Hello, we are looking for some guidance about possibly using a custom form
for the default new mail message in Outlook. We would like to add a custom
field so folks can enter a project number underneath the subject line and
search for it later - based on these posts & information found this seems
easy enough to do. We are using Exchange 2007 with Outlook 2007 and when
someone clicks 'new message' the thought was to provide a custom form with
this additional field.

However, my question is if this is a best practice and supported? It seems
there are conflicting posts or possibly different scenarios in which this
should or should not be done. I have followed the following link and seen
this site reference many times
(http://www.outlookcode.com/article.aspx?id=39) where it states this should
not be done but this seems to be one of the few places documenting this. My
concern is implementing something that may work now, only to fail later on
after a Service Pack or version migration.
Any guidance with reference to additional information or other suggestions
would be appreciated Thank you.