The AppendMessage method appends the specified text to the
current message. This method will cause the current thread to block
until the article transfer completes, a timeout occurs or the
transfer is canceled. During the transfer, the OnProgress
event will fire periodically, enabling the application to update any
user interface objects such as a progress bar.
This method is useful for composing a message where the
application needs to dynamically create the header, followed by a
large amount of text. The message contents should be text, with each
line terminated with a carriage return and linefeed character. Not
all mail servers support sending 8-bit characters, so the message
contents may need to be encoded if it uses anything other than
standard US ASCII. To append binary data, it must be encoded using
either the uucode or base64 (MIME) algorithms. It is recommended that
you use the Mail Message control to handle file attachments and other
complex message types.