[OK, I'll post this as a new answer to keep this one clean without deleting all of the previously posted content.]
I have just repeated the research mentioned in my other answer and it seems that things have greatly improved in the last three years. Both Outlook 2003 (SP3) and Outlook 2007 (SP2) now automatically recognize all of the protocols listed in the MS product support mail quoted in the NG thread linked from my older answer, including the url:
-protocol!
The latter means that you can now write something like:
url:irma:whatever
and have it properly linkified and handled. Outlook will however display a security confirmation dialog before executing the protocol handler.
Update: Note that in Outlook 2003 SP3 the new protocols (e.g. url:
, mms://
, etc.) are only auto-linkified in HTML-mails. The plain-text inspector behaves as described in my other answer. It does work with plain-text mails in Outlook 2007 SP2, however.
I have still found no hints at the ability to simply register custom protocols within Outlook that would work without the url:
-prefix, however.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…