You can add x-headers using any of the API's you mentioned. You can also do
it using Outlook 2007 code and the PropertyAccessor. There's an example of
adding an x-header on the Redemption web site, that with modifications can
also be used to add x-headers using CDO or ExMAPI.

The headers remain as named MAPI properties in the namespace
{00020386-0000-0000-C000-000000000046}until the item is sent out, then the
transport converts the MAPI named properties into x-headers (the named
properties remain on the item).

--
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007
Reminder Manager, Extended Reminders, Attachment Options
http://www.slovaktech.com/products.htm


"Lukas" wrote in message
...
I'm writing an application as plugin to Outlook 2003 using VSTO.
Now I have a big problem. I tried to add envid,notify and ret parameters
to
message header (MailItem) programmically but I got stuck.
According to SMTP specification, envid and ret must be added to RCPT
command.

This line should look like this

MAIL RET=HDRS ENVID=QQ314159

and recipient like

RCPT NOTIFY=SUCCESS

The problem is how to add these parameters to message header. I looked
into
vsto MailItem and Recipient classes and i didn't find appropriate
solution.
Is it possible to do it using REDEMPTION libary, CDO or Extended MAPI ?

Thanks for any ideas