Fax Sending Error

[Noro]

Hello,
I develop an ASP.NET 2.0 Intranet with a feature of sending messages through
an Exchange Server 2003. For e-mails sending, all passes well.

We have a Fax solution (RTEFAX) with Exchange connector who allows us to
send faxes from Outlook with the syntax [fax:[phone]], however when I try
to send a fax from my aspx page in the same way as from Outlook, I receive
the following message :
"The specified string is not in the form required for an e-mail address"

Here is the part of the code that generate the error :
.....
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
message.To.Add("[fax:[phone]]");
.....

My purpose is to send the fax to Exchange Server in e-mail format, so that
the RTEFAX Exchange connector gets back and send it in fax.

Please let me know if you have any idea
Any help is much appreciated. Thanks
Noro