A user defined MIME header does not produce the desired results in a Notes view.
Diagnosing the problem
As per Technote 1192072, in order to display a value within a view column, you must use a Summary type field with the Summary field flag. MIME header objects do not contain the Summary flag, with the exception of the MIME-Version field.
Resolving the problem
The above Technote provides a sample agent which can be used to create a new field from a MIME header, which will provide a Summary flag. However, if the MIME header to be used is a user-defined header, it will be easier to have the generating application create an X-Notes-Item header. X-Notes-Item headers are converted into Notes fields by the router.
In your Inbox view, you wish to have a column indicating security clearance on specific mails. The field can have the following values:
1 = Public
2 = Internal
3 = Restricted
You will store this value in a field called SecurityCategory. If you generate a MIME header of this name, it will not have the required Summary flag. Instead create a header as follows:
X-Notes-Item: n; name=SecurityCategory
where n has a value of 1, 2 or 3. The router will convert this field to a Notes field with a Summary flag and the column can have a formula as follows:
@If( SecurityCategory = "1" ; "PUBLIC";
SecurityCategory = "2" ; "INTERNAL";
SecurityCategory = "3" ; "RESTRICTED";