It appears Smart Tags Are only for editing in Outlook, what about.

[Mickbags]

I am trying to define smart tags that will be used to process an
incoming message. However it does not work if I am viewing the
message. When I compose a message I see the smart tags
invoked. Is it true it is impossible to force this? It may work if
the incoming message is rich text but many messages are not and
I do not know how to force every incoming message to be rich text.

 

[Sue Mosher [MVP-Outlook]]

Smart Tags are a feature of Word and Excel. Therefore, they work in Outlook
only on items where Word is the email editor. This would include all
messages composed in Outlook and rich-text messages received if Outlook is
set to use Word on received rich-text messages (Tools | Options | Mail
Format).

One possible approach that doesn't depend on the format would be to forward
the message and perform the processing on the forwarded message, which will
be using Word as the email editor (assuming that's your setting), regardless
of the format.