Found that when I used MS outlook 2003 client to send out mail to external,
there's no disclaimer. But, when using RFC command (telnet port 25 of
exchange server) to send out, it's ok.
How to convert the message from mapi format to smtp format when sending out?
MAPI isn't a message format, nor is SMTP. I would suggest you look into
alternatives to the event sink method - check out Exclaimer or GFI (they
make a free disclaimer add-in).
Are there any freeware to enable disclaimer in exchange 2003?
Yes - as I wrote, the GFI tool is free.
Ah. Sorry about that.
According to this: http://www.gfi.com/offers/q2freeware.asp?adv=794&loc=99
they will hav a free replacement soon.
Other than that, I don't know of anything. Exclaimer isn't expensive, tho.