EmailDLL Online Manual
Parameters: FileName, a string indicating the filename
Returns: Success or Error Status
Use this method to name a file whose text is added to the message text . The file should be text file, with the same restrictions on characters as the rest of the message body: seven-bit ASCII only. The contents of the file are added to the message after any text applied with the Email.AddMessageLine() method. The position in the message of the file contents is not affected by the order in which you specify the file or add text. The file text is always applied at the end of the message.
To clear this setting, simply pass an empty string to this method. This should be used when one message requires a file, but a subsequent one does not.
Note that the file you specify with this method is not an attachment to the message. If you have added message text using the Email.AddMessageLine() method, then the file acts more like a signature file. If you don't add any message text with the Email.AddMessageLine() method, then the file you specify here is more like a form letter.
This method takes a string as an argument. The string must contain the name of a file to which the user running the IntraBuilder server would have read access. If the file is currently in use and unable to be read, then the message won't be correctly transmitted, and an error will be returned upon calling the Email.SendMessage() method.