Why does CDO.Message give 800C000D errors?

You might see this: 
 

CDO.Message.1 (0x800C000D)  The specified protocol is unknown.

 
There are various reasons for this to happen. Here are some code samples to reproduce this error message: 
 
CreateMHTMLBody 
 
This can be caused if you forget the protocol on your URL, or just put a filename. For example: 
 

<!--       METADATA       TYPE="typelib"       UUID="CD000000-8B95-11D1-82DB-00C04FB1625D"       NAME="CDO for Windows 2000 Library"   -->   <%       Set cdoConfig = CreateObject("CDO.Configuration")         With cdoConfig.Fields           .Item(cdoSendUsingMethod) = cdoSendUsingPort           .Item(cdoSMTPServer) = "<enter_mail.server_here>"           .Update       End With         Set cdoMessage = CreateObject("CDO.Message")         With cdoMessage           Set .Configuration = cdoConfig           .From = "from@me.com"           .To = "to@me.com"           .Subject = "Sample CDO Message"           .CreateMHTMLBody "page.asp"          .Send       End With         Set cdoMessage = Nothing       Set cdoConfig = Nothing   %>

 
Make sure you get the URL right. CDO.Message does not understand relative URL formats; it has to be the FULL URL. 
 

<%      ' ...        .CreateMHTMLBody "http://server/page.asp"        ' ...  %>

 
If your URL is in the correct format but the server cannot be found, you will get: 
 

CDO.Message.1 error '800c0005'   The system cannot locate the resource specified.

 
If the server is valid but the page cannot be found, you will get: 
 

CDO.Message.1 error '80040218'   Unknown Error

 
And if you reference a page that has an error, you might get an even less helpful response: 
 

error '8004021a'

 
(No error message text.) 
 
If you have something like: 
 

<%      ' ...        ' note that http is missing a t      .CreateMHTMLBody "htp://server/page.asp"        ' ...  %>

 
You will get: 
 

CDO.Message.1 error '800401e4'   Invalid syntax

 
AddAttachment 
 
Many people use .AddAttachment method to add a file to an outgoing message. However, they don't realize that you need to give it a full path, rather than just a filename. The following should reproduce the error: 
 

<!--       METADATA       TYPE="typelib"       UUID="CD000000-8B95-11D1-82DB-00C04FB1625D"       NAME="CDO for Windows 2000 Library"   -->   <%       Set cdoConfig = CreateObject("CDO.Configuration")         With cdoConfig.Fields           .Item(cdoSendUsingMethod) = cdoSendUsingPort           .Item(cdoSMTPServer) = "<enter_mail.server_here>"           .Update       End With         Set cdoMessage = CreateObject("CDO.Message")         With cdoMessage           Set .Configuration = cdoConfig           .From = "from@me.com"           .To = "to@me.com"           .Subject = "Sample CDO Message"           .AddAttachment "file.txt"          .TextBody = "This is a test."          .Send       End With         Set cdoMessage = Nothing       Set cdoConfig = Nothing   %>

 
CDO.Message does not have any context for the location of the script that is calling it. So it has no idea that the file is supposed to come from the same folder as the script, if that was your intention. Include the full local path to the file (you can still use Server.MapPath here). The following are all valid formats, assuming the files exist: 
 

<%      ' ...        .AddAttachment Server.MapPath("file1.txt")      .AddAttachment "d:\file2.txt"      .AddAttachment "file://d:\file3.txt"        ' ...  %>

 
And no, the same error message isn't raised if you attach a file that doesn't actually exist. If you specify such a filename, you will get: 
 

CDO.Message.1 error '80070002'   The system cannot find the file specified.

 
And if you try to attach a file from a folder or drive that doesn't exist (e.g. if you made a typo in the path), you will get: 
 

CDO.Message.1 error '80070003'   The system cannot find the path specified.

 
Make sure IUSR (or the authenticated user) has access to the file(s) and folder(s) you are accessing. Otherwise, you will see this: 
 

CDO.Message.1 error '80070005'   Access is denied.